PORTLAND, Ore. (KOIN) — A late-September fire that collapsed an abandoned building in Southeast Portland and endangered firefighters inside was determined to be “caused by human action,” an investigator with Portland Fire & Rescue told KOIN 6 Wednesday.

The investigation, led by PF&R’s Arson Investigation Unit, has not revealed any additional details beyond human involvement.

PF&R crews first responded to the significant, four-alarm fire near SE 9th Avenue and Southeast Alder Street around 12:30 a.m. Sept. 24.

Firefighters said when they arrived, they saw flames bursting out of the windows.

Around 2:30 a.m., the building partially collapsed in the midst of the firefighting efforts. By the time the sun rose, the majority of the structure had fallen.

Ultimately, there were no injuries and no evacuations were made, and crews were able to save two adjoining buildings.

Officials said they know this abandoned site well as they’ve responded to multiple fires at the building in the past.

KOIN 6 will update this coverage with more details as they are released by investigators.