At least three houses were destroyed, and a fourth was heavily damaged, in an apparent explosion Saturday in Allentown, officials said.

Authorities evacuated nearby houses as a precaution following the 1:30 p.m. blast. Fire department, police and paramedics were responding, although it was not immediately known if there were any injuries.

"All I heard was a big boom," said neighbor Holly Ache. "My whole house just shook. My windows broke. I went out the front door and I looked down the street and the houses were gone. They blew up."

A large cloud of smoke was visible from the city's downtown.

An explosion a day earlier in nearby Bethlehem that destroyed a duplex was most likely caused by a gas leak, officials said. No injuries were reported.