"They are currently contained," the police spokeswoman confirmed. "Police are working with experts to safely return them to their facility.
"There is no immediate danger to the public but people are advised to avoid the area."
NSW Health has been contacted for comment.
The use of primates for medical experiments at RPA and a number of other Sydney hospitals and universities was revealed in 2016.
Earlier, a woman told 2GB that her daughter, who worked at the hospital, had seen the baboons.
"My daughter is an occupational therapist at RPA and she said "yes mum I just helped wrangle them," she said to 2GB.
It's not the first time animals have been loose in Sydney's inner west.
In 2014, water buffaloes broke free while filming a Korean Samsung commercial and travelled for more than two kilometres before being caught by authorities.
