Police believe the incident began as a fight at Qin's Asian Bistro and Bar at 5007 Lone Tree Way.
Some people involved in the fight there left and were traveling westbound on state Highway 4 when one vehicle pulled up next to two other vehicles and began shooting, according to the Police Department. Two vehicles were struck by gunfire.
The victims then went to Johnny B Sports Bar. At about 1:25 a.m., while officers were conducing a security check at the sports bar at 2500 Sycamore Drive, two vehicles arrived in the parking lot and another fight started, police said.
One of the Highway 4 victims, Eric Jones, a 34-year-old Pittsburg man, was transported to a local hospital, where he was pronounced dead, according to the Contra Costa County coroner's office.
A 25-year-old woman and a 46-year-old woman, also Pittsburg residents, were shot as well, according to police. They received moderate injuries and were released.
No suspects have been arrested.
Anyone with information regarded to the shootings is asked to contact Detective Castillo at (925) 779-6933.