PHILADELPHIA (CBS) -- Police say a fight inside a bar led to the shooting of three people overnight in Strawberry Mansion.

It happened around 2:30 a.m. Saturday at 29th Street and Ridge Avenue.

Police say there was an altercation at the bar and that's when private security guards heard gunshots.

"They saw a person firing and they returned fire," said Captain Mark Overwise. "Three security guards total returned fire. There was a total of 19 shots fired by security guards."

A woman was shot in the back and was taken to Temple University Hospital in critical condition. A man was shot in the stomach and was listed in stable condition. A second man suffered a graze wound to the head.

The shooting remains under investigation.