The shooting was reported about 9:45 p.m. in a parking lot in the 1100 block of School Street, where officers found a man and a woman with gunshot wounds.
The officers and medical personnel began lifesaving measures but the man died at the scene. The woman was taken to a hospital, where she later died. Their names were not released.
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The shooting may have followed an argument involving three people in the parking lot, where one person produced a gun and started shooting, according to a release from the Suisun City Police Department.
No arrests have been made and a description of the suspect was not available.
Detectives are asking that anyone with information about the shooting to contact the Suisun City Police Department at (707) 421-7373.