Police received a call at 1:36 a.m. that a shooting had occurred at Cruisers Saloon at 1611 A St.
Apparently a group of men who had been kicked out of the bar earlier in the night returned to the bar to start a fight, police said.
A fight ensued inside the bar and then moved just outside the front door.
One of the men who had been kicked out earlier then pulled out a handgun and fired at least one shot inside the bar, police said.
A 38-year-old man at the bar was hit and died at the scene, police said.
The homicide is under investigation, police said.
Anyone with information is asked to call Antioch police Detective Mike Mellone at (925) 779-6930.