Northern Arizona University shooting: One dead, three injured

One person has been killed and three injured in a shooting at a US university, just a week after a massacre at a college in Oregon left nine victims dead.

Northern Arizona University (NAU) announced on Twitter early on Friday that a gunman had opened fire at 1.20am at its Flagstaff campus, which has around 20,000 students. It later confirmed in a statement that four people had been shot, one of them fatally.

According to ABC News, the shooter has been identified as Steven Jones, an 18-year-old student at the college. NAU police chief Greg Fowler told reporters that a fight had broken out between two groups of students, and it was during this confrontation that Jones fired his gun.

He is now in police custody, Fowler said.

The incident took place outside Mountain View Hall, a domitory, on the north east end of the campus.

Last week's shooting at Umpqua Community College in Roseburg, Oregon, prompted calls for tighter gun laws across the US. President Obama, who has advocated for greater restrictions on gun ownership, told reporters that "prayers are not enough".

"As I said just a few months ago, and I said just a few months before that, and I said each time we see one of these mass shootings, our thoughts and prayers are not enough," he said during a White House briefing after the massacre.

"We are not the only country on Earth who has people with mental illnesses who want to do harm to other people," he said. "[But] we are the only advanced country on Earth who sees these kinds of mass shootings every few months."