At least nine people were shot -- one fatally -- at a West Philadelphia birthday block party in the early hours of Saturday morning, police said Sunday.

A 19-year-old man was killed during the shooting, in which police believe more than one gun was used. The man who was killed had gunshot wounds to his face and body, authorities said.

The shooting was reported at around 1.30 a.m. Saturday, according to police.

"We were all standing on the porch. Next thing you know we're hearing gunshots," a 22-year-old woman who was not identified told CNN affiliate KYW. "Everybody gets down. We're running in the house, jumping over people."

She told KYW one victim, who was shot in the legs, was laying on top of her after they both ducked for cover during the chaos.

When officers arrived, they saw a large crowd of people and found multiple gunshot victims, a Philadelphia police spokesperson told CNN. Authorities have not arrested anyone and have yet to determine what led to the gunfire.

There were more than four dozen shell casings found at the scene, according to police. The number of shooters is unclear, they said.

Six other victims, five women and one man, were transported to Presbyterian Hospital after the shooting and are listed as stable.

Two 17-year-old girls arrived at a hospital Saturday afternoon, according to police. One had a gunshot wound to her lower leg, and another had a wound to her inner thigh, police said.