A father and a 8-year-old son were killed in a multiple shooting that erupted at a Riverside restaurant in southern California Saturday afternoon, the authorities said.

A 56-year-old man, who was armed with two pistols and was riding on a bicycle, went inside a Del Taco restaurant shortly after 1 p.m.(0800 GMT),walked up to a table where a husband and wife and their two sons were eating together.

The husband died at the scene and a boy was pronounced dead at Arrowhead Regional Medical Center. The 29-year-old mother and her 5-year-old son were rushed to a local hospital and were in critical condition.

The gunman then turned the gun at himself and was declared dead of a self-inflicted gunshot wound to his head.

Police said the gunman was the stepfather of the woman, and she was shot as many as 10 times. The man had a criminal history dating to 1972 that included convictions for theft and assault with a deadly weapon. He was last arrested in 1999.

Officials are investigating the shooting as a domestic violence situation.

The victims are San Bernardino residents, and the gunman was thought to have some ties to the county in the eastern suburb of Los Angeles city.