Four people were shot at the north Vallejo park during a picnic and barbecue around 8:15 p.m. They were driven to Kaiser Permanente Vallejo Medical Center and Sutter Solano Hospital.
One of the victims, 58-year-old Homer Woodrow, of Vallejo, died at Sutter Solano Hospital.
A 67-year-old woman and a 17-year-old boy, both of Vallejo, were in critical condition after the shootings. A 35-year-old Vallejo man also was shot in the arm. The names of the victims have not been released.
At least one occupant in a dark-colored van opened fire on the victims in the park, Sgt. Kevin Coelho said.
Police issued a murder and attempted murder arrest warrant Wednesday for 18-year-old Gregory Joseph Bethany Jr., who fled to Arizona after the shootings, Coelho said.
Vallejo, Phoenix and Los Angeles police tracked Bethany from Phoenix to Los Angeles and arrested him Tuesday, Coelho said.
Bethany admitted to Vallejo police during questioning in Los Angeles that he was involved in the shootings, Coelho said.
Vallejo police also searched two Vallejo homes associated with Bethany and recovered a .223-caliber rifle believed to be the murder weapon, Coelho said.
Police have not disclosed a motive for the shootings. Bethany will be transferred to Solano County, Coelho said.