A mass shooting in Philadelphia, USA, left at least three people dead and 11 others wounded, police said on Sunday, Reuters reported.

A gunman opened fire in Philadelphia's busy South Street area, which has multiple bars and restaurants, around midnight on Saturday. Two men and a woman were killed, officials said.

"There were hundreds of individuals just enjoying South Street, as they do every single weekend when this shooting broke out," Philadelphia Police Inspector D. F. Pace said.

Philadelphia police officers observed "several active shooters shooting into the crowd," with one officer "within about 10 to 15 yards" of an individual firing into the crowd, police said. That officer fired at the suspect, they said.

The whereabouts of the shooters were not immediately known, Pace said. Two handguns were recovered at the scene, including one with an extended magazine, he added. 

There were no immediate arrests.