ROSEBURG (Oregon) • The father of the gunman who killed nine people at a community college has called on the United States to change its gun laws, saying the massacre would not have happened if his son had not been able to buy more than a dozen handguns and rifles.

"How was he able to compile that kind of arsenal?" Mr Ian Mercer said in an interview with CNN at his home in Tarzana, California. He said he had no idea that his son owned any firearms.

The gunman, Christopher Harper-Mercer, died of a self-inflicted gunshot wound after exchanging fire with police officers who had responded to the shooting at Umpqua Community College on Thursday morning. Law enforcement officials said they had found another gun at Harper-Mercer's apartment, the 14th they had confiscated.

All the weapons had been purchased legally by Harper-Mercer or a relative, the officials said.

Despite Harper-Mercer's online interest in high-profile shootings and neighbours' memories of him as an enthusiastic gun collector who frequently went target shooting with his mother, the gunman's father told CNN he had not known that his son owned guns.

Harper-Mercer's parents divorced a decade ago and he lived with his mother. Mr Mercer said he had not seen his son since he and his mother moved to Oregon about two years ago, but said there had been no "disharmony or any bitterness" between them.

Adding a raw personal voice to the debate over gun control, Mr Mercer said the US needed to tighten its gun laws.

"It has to change," he said. "How can it not? Even people that believe in the right to bear arms, what right do you have to take someone's life?"

He would not discuss his son's mental health issues, deferring to the police investigation. "Obviously, someone who goes and kills nine people has to have some kind of issue," he said.

Standing on his lawn, Mr Mercer said the shooting had devastated his family. "But we're not alone in this," he said. "My heart goes out to all the families that were affected by this."

Harper-Mercer, a student at the community college, was armed with six guns, spare ammunition magazines and body armour when he walked into a writing class and opened fire on Thursday morning.

A new timeline of the response to the shooting showed that officers arrived five minutes after the first 911 emergency calls. Two minutes later, they had engaged Harper-Mercer. Two minutes after that, they reported, the shooter was down.

NEW YORK TIMES