HACKETTSTOWN, N.J. -

A sinkhole that has already damaged two homes in Hackettstown, Warren County grew larger on Saturday, police said.

The sinkhole was first discovered Thursday following a water main break in the 100 block of College View Drive. On Saturday, it continued to grow, causing part of a resident's driveway to collapse, police said.

Police said two homes have damage to their foundations. At this point, the damage is not severe enough to force the homeowners to evacuate.

Nonetheless, officials are closely monitoring the situation as they fear the 40-foot sinkhole could continue to expand. An engineer visited the site on Saturday, but was unable to locate the main source of the sinkhole. More experts are scheduled to return on Monday in hopes of pinpointing the source.

"We're concerned about the weather warming up and causing the ground to collapse more," said Hackettstown police Sgt. Darren Tynan.