Philadelphia police say a man fired several shots into a crowd of people attending a pre-prom party at a home, killing another man.

The shooting occurred around 8:45 p.m. Thursday.

Authorities believe the gunman had been among those attending the party, but it wasn't immediately clear what sparked the shooting. Roughly 70 people were at the party, ranging in age from infant to adult.

The gunman fired as many as six shots into the crowd, and a 23-year-old man was shot in the head. He was taken to a hospital and was pronounced dead there early Friday. His name has not been released.

No other injuries were reported.

The party was being held in honor of a 17-year-old boy who had left the party shortly before the shooting occurred.