(CNN) One suspect has been arrested in downtown Seattle's deadly shooting, and police are looking for two, the mayor said Thursday.

"Both men are considered armed and dangerous," the police department said. Police said they arrested 21-year-old Jamel Jackson on a firearms violation.

One person died and seven were injured in the shooting reported Wednesday afternoon near Fourth Avenue and Pine Street, near Westlake Park, police tweeted.

"SPD has arrested and booked one of the shooters," Mayor Jenny Durkan said at a press conference. "The other two shooters were also known to SPD, and have extensive criminal histories and gang connections."

The suspect arrested Thursday was one of the seven people taken to the hospital with gunshot wounds, Police Chief Carmen Best said. He was seen on surveillance video with a gun in his hand, Best said.

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