Police sources say two of those killed were innocent bystanders.
PHILADELPHIA (WPVI) -- Philadelphia police are reviewing a video that appears to capture the moments leading up to a deadly mass shooting on South Street Saturday night.
The shooting happened around 11:30 p.m. and left three people dead and 11 others were shot and wounded.
Police sources say two of those killed were innocent bystanders.
The third victim, according to sources, is 34-year-old Greg "Japan" Jackson. He is the man seen on video wearing a white shirt. The video appears to show him pulling a gun out of his waistband before the shootout on the 200 block of South Street.
SEE ALSO: What we know about victims killed in South Street mass shooting
A man seen wearing a black t-shirt in the video was also shot and is in critical condition.
Authorities say officers assigned to the area heard the initial gunfire and quickly responded. Upon arrival, officers found several gunshot victims and an unknown man firing into a crowd of people, said Philadelphia Police Commissioner Danielle Outlaw during a Sunday afternoon briefing.
One officer pulled out his weapon and fired several times in the direction of the gunman. Police say the gunman fled, but it's believed he was hit by the officer's gunfire.
Philadelphia police confirm they received intel of potential problems on South Street and several other areas of the city by monitoring social media.
Mayor Jim Kenney told Action News there were 70 police officers in the immediate vicinity due to nearby events.
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The crowd along South Street swelled sometime after 8 p.m.
Action News asked city leaders what was done to disperse the crowd before the shooting. Police say it's too early to tell, adding that it's part of the investigation.
No arrests have been made at this time.
Anyone with information is asked to call police at 215-686-TIPS.