BEAVERTON, Ore. -- Nine monkeys who escaped from cages at an Oregon Health & Science University campus have been recaptured, OHSU officials said Saturday.

The group of monkeys escaped when a caretaker cleaned an outdoor cage that housed the monkeys, said Jim Newman, an OHSU spokesman.

"One of our cage cleaners accidentally left a lock off a cage," Newman said. "The cage was closed; however, the animals were able to slide the door open and get out."

Of the nine monkeys that escaped, Newman said four monkeys were quickly captured. A fifth was caught Friday night and three more were captured by Saturday night.

The final monkey was captured at 2 p.m. Sunday on the OHSU primate center campus.

The monkeys were seen Friday along the south edge of the university's west campus on Southwest 185th Street in Beaverton -- an area near the MAX light-rail line, Newman said.

The snow monkeys weigh between 20 and 50 pounds. They're too fast to catch, so caretakers were trying to lure them into cages baited with apples.

Amy Fuller, who lives in the area, snapped a photo of the monkeys on the roof of an apartment complex.

"I was talking to my Mom on the balcony in the morning and looked over and I saw something was walking on four legs," Fuller said. "I thought it was a stray dog and it looked at me and I thought, 'Ok, that's not a stray dog.'"

The primate center affiliated with OHSU has long been criticized by animal-rights groups, who say the research monkeys are mistreated. Newman said OHSU does not believe the employee who forgot to lock the cage is an activist who got a job at the primate center.

Rachelle Rock, who works in the area, said she has seen monkeys in the trees near the MAX line before Friday. Rock said she's not concerned about the four monkeys that remain at large.

"I personally would not be afraid of them," she said. "I wouldn't go up and touch them, but I would enjoy it if they were in the tree nearby."

Newman said the escapees are breeding monkeys and no tests were being conducted on them. He said chances are low that a human would contract a disease from a monkey

"Someone would have to be able to corner a monkey, capture a monkey, get bitten by a monkey. The monkey would have to be a carrier of the disease and the disease would have to be shedding at that very moment," Newman said. "So all of those scenarios would have to line up for someone to capture a disease."