PORTLAND, Ore. (KOIN) — Two adult rhesus macaques died in an accident at Oregon Health & Science University’s Oregon National Primate Research Center earlier this month.

OHSU said the accident happened on August 13 when a technician turned on a cage washing machine without realizing there were two monkeys still inside the top cages. A vet was called immediately once the technician realized, but it was too late. One of the monkeys died and the other had to be euthanized.

OHSU’s Institutional Animal Care and Use Committee is conducting an internal investigation, and they reported the accident to regulatory agencies that oversee animal research.

Over 5,000 primates live at the lab, which has been the source of complaints by watchdog groups and PETA in the past.

OHSU says they adhere to all regulations are and regret the accident. They said the primates serve critical roles in researching cures for diseases, including COVID-19.