More than half of the 43 monkeys bred for medical research that escaped from a South Carolina facility last week have now been safely recovered, officials reported on Sunday.

Twenty-four monkeys were captured on Sunday, following the recovery of another one of the 43 that had escaped the day before.

A “sizeable group” of monkeys is still active along the compound’s fence line, having settled in the trees for the night, according to police in Yemassee, located about 50 miles (80 kilometers) northeast of Savannah, Georgia. Veterinarians have been assessing the animals, and initial reports indicate they are all healthy.

The Rhesus macaques escaped on Wednesday after an employee at the Alpha Genesis facility in Yemassee failed to fully secure a door while feeding and checking on them, officials explained.

Since their escape, the monkeys have been seen exploring the outer fence of the Alpha Genesis compound, vocalizing to those still inside. On Saturday, they continued to engage with their companions within the facility, which police described as a positive sign.

Alpha Genesis CEO Greg Westergaard stated that efforts to recover all the monkeys will persist until they are all found.

The monkeys, which are about the size of a cat, are all females weighing around 7 pounds (3 kilograms).

Both Alpha Genesis and federal health officials have confirmed that the monkeys do not pose a public health risk. The facility breeds these monkeys for sale to medical and other researchers.

According to its website, Alpha Genesis supplies primates for research purposes globally from its Yemassee facility.