(CNN) -- Authorities are seeking multiple people suspected of firing into a crowd outside a Philadelphia bar Saturday night, wounding at least nine, police said.

The gunfire erupted just before 11 p.m. ET in the Kensington neighborhood, First Deputy Commissioner John Stanford of the Philadelphia Police Department said at a news conference early Sunday.

"Multiple suspects" jumped out of a vehicle and opened fire on a crowd outside, Stanford said, then fled in the vehicle.

The suspects "may have spotted someone that they wanted to shoot at, exited the vehicle and just began firing at the group of individuals that were there," Stanford said. Police are working to establish a motive.

Police say they have not yet found any weapons or arrested anyone.

All nine adult victims were transported to a hospital, according to police. Five of them, including a 24-year-old Hispanic man, a 25-year-old Black man, a 24-year-old Black man, and two white 40-year-old men, were listed in critical condition.

Four others, including a 23-year-old Black man, 23-year-old Black woman, and two 24-year-old Black men, were listed in stable condition.

The shooting took place in a high traffic area that was heavily patrolled by officers on Saturday night, he said. A narcotics strike force had been conducting an operation further along the block earlier Saturday evening and officers from the team heard the shots.

"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," Stanford said.

At least 40 pieces of ballistic evidence have been recovered, he said.

The gunmen were seen exiting a black vehicle and police have asked those in the area to assist with additional information. It had been a warm evening with many people out on the streets and there were a number of businesses near the scene of the shooting, Stanford said.

"We'll try to gather video and hopefully be able to get some additional information as well as video surveillance that may be able to help us identify who was responsible for this," he said. "This is an area that's always busy."

There have been 585 mass shootings in the US so far this year, defined as a shooting with four or more people injured, excluding the shooter, according to the non-profit Gun Violence Archive. At that rate, the number of mass shootings is likely to be similar to last year's total of 691.

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