A man whose son is among six dead in a shooting in California has blamed politicians and the gun lobby, asking in an emotional and at times angry speech: “When will this insanity stop?”

Richard Martinez choked up several times as he paid tribute to his son who was killed on Friday when a gunman opened fire in a bustling California college town – the latest armed massacre in the United States and one likely to trigger more passionate debate about gun rights.

“My son’s name was Christopher Ross Martinez, he was 20 years old and he died last night,” Martinez told reporters, his face contorted with despair and rage.

“Our family has a message for every parent out there: you don’t think it’ll happen to your child until it does,” he said, reading from a family statement.

“Chris was a really great kid, ask anyone who knew him. His death has left our family lost and broken.”

His voice shaking with emotion, Martinez rounded on politicians and the powerful National Rifle Association.

“Why did Chris die? Chris died because of craven, irresponsible politicians and the NRA,” Martinez said, raising his voice.

“They talk about gun rights. What about Chris’s right to live? When will this insanity stop? When will enough people say stop this madness? We don’t have to live like this.

“Too many have died. We should say to ourselves: ‘Not one more.’

“Thank you, that’s it,” he added, punching the air.

Peter Rodger, an assistant director of the 2012 Hollywood blockbuster The Hunger Games, believes the attacker was his 22-year-old son Elliot, lawyer Alan Shifman told reporters separately, although that was not immediately confirmed by police.