McKEESPORT, Pa. -- Hundreds of people are told to leave their businesses when a roof came tumbling down on Friday.

The collapse is in McKeesport, and the town's mayor has declared an emergency so the cleanup effort can begin.

A roof of a building on Shaw Avenue collapsed overnight, sending bricks flying into nearby businesses.

Emergency crews have evacuated surrounding buildings, including a day care center.

Police have blocked off streets around the collapse.

No injuries have been reported.