PORTLAND, Ore. (AP) — Protesters returned to the streets of Portland, following a pause largely due to poor air quality from wildfires on the West Coast.
Police declared an unlawful assembly Friday night in a neighborhood near a U.S. Immigration and Customs Enforcement building where protesters had marched. Demonstrators participated in criminal activity and threw items at officers, police said, leading to 11 arrests.
Demonstrators had not gathered in the city since at least September 9, when police and protesters clashed near City Hall. Wildfires have spewed dangerously dirty air across Oregon, California and Washington state, and sent haze across the country.
PORTLAND, OR – SEPTEMBER 18: Federal officers disperse a crowd during a protest at the Immigration and Customs Enforcement detention facility on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: A protester taunts federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: A federal officer watches the crowd during a protest at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: A note advises a car owner of tear gas exposure during a protest at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Federal officers disperse a crowd during a protest at the Immigration and Customs Enforcement detention facility on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Federal officers guard the front gate of the Immigration and Customs Enforcement detention center during a protest on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: A damaged umbrella shield lays abandoned following a crowd dispersal by federal officers at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Expended less lethal canisters line the street under the feet of federal officers during a crowd dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Federal officers watch the crowd during a protest at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Protesters use umbrellas to block less lethal rounds fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Federal officers disperse a crowd during a protest at the Immigration and Customs Enforcement detention facility on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 19: Portland police arrest a protester during a dispersal at the Immigration and Customs Enforcement detention center early in the morning on September 19, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Two activists embrace during a protest at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 19: A tear gas canister fired by federal officers burns under a parked car during a protest at the Immigration and Customs Enforcement detention center early in the morning on September 19, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 19: Federal officers disperse a crowd during a protest at the Immigration and Customs Enforcement detention facility early in the morning on September 19, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 19: A protester moves through smoke fired by federal officers during a dispersal at the Immigration and Customs Enforcement detention center early in the morning on September 19, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
PORTLAND, OR – SEPTEMBER 18: Portland police arrest a protester during a crowd dispersal at the Immigration and Customs Enforcement detention center on September 18, 2020 in Portland, Oregon. Protests against police brutality and racial injustice resumed Friday, after activists called for a pause in response to hazardous air quality from nearby wildfire smoke. (Photo by Nathan Howard/Getty Images) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Police try to take control of the streets during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Police arrest a protester as they try to take control of the streets during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Police stand guard during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air as police make a line of control during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Protesters stand off with police during protests Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Federal police try to take control of the streets during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein) 
Tear gas fills the air as police take control of the streets during protests, Friday, Sept. 18, 2020, in Portland, Ore. (AP Photo/Paula Bronstein) 
Tear gas fills the air during protests, Friday, Sept. 18, 2020, in Portland, Ore. The protests, which began over the killing of George Floyd, often result frequent clashes between protesters and law enforcement. (AP Photo/Paula Bronstein)