Sightings of the monkeys have been reported in the O’Fallon Park neighbourhood in the north of the city, and Hauser believed they were still in this area on Sunday.
“Original reports suggested there were four animals, but we cannot confirm an actual number at this time, only that there is more than one,” Hauser said.
Marva Young, who lives in the neighbourhood, told local news network KSDK: “I think of the danger, because that’s a wild animal.”
Another resident told the network it was “crazy” that they could be nearby.
Pictures of the primates perched on a porch-side wall and standing on two legs near a parked car have been shared on social media.
Animal care and control officers have patrolled the area but have not yet managed to locate the monkeys.
“We are working to get an idea of where they may be hiding or seeking food,” Hauser said.
“We want to stress that residents should not approach these monkeys or try to capture them.”
Instead, people should report sightings to the health department, he said.
“Once captured, the monkeys will be transported to a facility certified to care for exotic animals.”