At least nine people were shot in Philadelphia on Saturday night, leaving two in critical condition, the police said.
Multiple shooters exited a vehicle in the Kensington area of the Pennsylvania city and began shooting, firing about 40 shots, Philadelphia First Deputy Police Commissioner John Stanford told a televised news briefing.
The injured were in hospital, seven of them in stable condition, he said.
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The target of the shooters, who returned to the vehicle and left, remained unknown, Stanford said, adding that police were investigating.
The bloodshed follows a series of US school shootings that have left dozens dead and wounded this year alone, adding to a long-running US debate over gun control. One of the deadliest took place in May when a gunman killed 19 children and two adults in Uvalde, Texas.
One person was killed and about 20 wounded on Halloween night in shootings in Kansas City and Chicago.