More than 40 monkeys were on the loose Thursday in a small US town after escaping a research facility, with authorities warning residents to keep their doors and windows closed.

The rhesus macaques — described as “skittish” by police in Yemassee, South Carolina — were reported to have fled their enclosures a day earlier at a facility run by Alpha Genesis, which specializes in primate-based biomedical research.

Search teams were deployed to help locate the monkeys and were “working to entice them with food,” the local police department said on social media.

“Residents are urged to keep their doors and windows securely closed and to report any sighting immediately by dialing 911. Please do not attempt to approach these animals under any circumstances,” it said.

The police force added that all the 43 primates were young females weighing up to seven pounds (three kilograms), and that they had not been used for testing.

“A spokesman from Alpha Genesis can confirm that these animals are too young to carry disease,” it said.

Greg Westergaard, CEO of Alpha Genesis, said the escape was “frustrating,” telling CBS News he is “hoping for a happy ending” with the primates returning of their own volition.

He said that the primates were able to roam free after a caretaker failed to secure a door at an enclosure.

“It’s really like follow-the-leader. You see one go and the others go,” Westergaard said.