Investigators say it happened around 10:45 p.m. Saturday near the intersection of Kensington and Allegheny avenues.
Police say multiple shooters exited a black vehicle and fired at least 40 rounds, striking nine people.
"Officers were out in this area. In fact, they heard the gunshots when they occurred," said First Deputy Commissioner John Stanford with the Philadelphia Police Department. "We have some brazen individuals in this city that don't care. They don't care how many police officers are out here, and some of them don't care in terms of how many people are out here."
Police say the victims are both male and female and range in age from 23 to 40.
On Sunday, police said four victims were listed as critical and five others were listed as stable at an area hospital.
Investigators are still trying to figure out a motive.
"At this point in time it looks like these individuals may have spotted someone they wanted to shoot at, exited the vehicle and just began firing at the group of individuals that were there," said Stanford.
Philly police provide update on shooting outside Kensington bar
Police are still searching for surveillance video that captured the gunfire.
Given the nature of this mass shooting, officers say everyone in that area should be worried.
"The fact that we have nine people shot, I think that's a public safety threat in itself and people have to be concerned about individuals shooting in this city," said Stanford.
Kensington and Allegheny is a busy intersection where people are frequently outdoors. Police say it may have been busier than normal too as Saturday night was warm and the Phillies were on the TV, drawing crowds out to the bars.
"You should be able to walk through the city streets and not have to worry about gunfire," said Stanford.
Chopper 6 overhead after shooting outside Kensington bar
Before the shooting, police say they were conducting a narcotics investigation up the block.
"This is an area that's always busy as many of you know. We have a heavy police presence down here. In fact earlier this evening, our narcotics strike force conducted a narcotics investigation just up the block," said Stanford.
Police are asking anyone who may have information on the shooting to give them a call.
In response to the mass shooting, Mayor Jim Kenney tweeted, "I'm appalled and devastated by this despicable, brazen act of gun violence. My heart is with the family and loved ones of those injured, and with everyone impacted by this tragedy."