San Leandro police Sgt. Mike Sobek says the victim and his family were walking to their car around 1:45 a.m. when they were confronted by a group of men who demanded their purchases. When the family refused, a fight broke out and one of the robbers shot the man.
Sobek says other family members wrestled down one of the suspects, who was taken into police custody.
Investigators are reviewing store surveillance video to identify at least three other suspects.
Witnesses say the Walmart parking lot was crowded with Black Friday shoppers at the time, and the store was briefly closed as police investigated.