Four people were hurt after a roach bomb exploded in a Brooklyn apartment building Thursday.

It happened just after 1 p.m. on Hegeman Avenue in Brownsville.

The gas and elevators were shut down temporarily as National Grid and emergency crews responded to the explosion.

Fire officials say windows on the second floor unit were blown out, but there was no visible damage on the upper levels.

The son of one of the residents says he's concerned for his mother's safety.

"It got me worried because she's on the 17th floor, she's an elderly woman," he said. "It has me worried like what happens if something does happen. She's on the 17th floor. How is she gonna get down here? They shut those elevators down. How's she gonna get down those steps?"

Three people were taken to Brookdale Medical Center for treatment.