Source: BBCNews
One person has been killed and three injured in a shooting at Northern Arizona University.
Police were called at 01:20 local time (08:20 GMT) after gunfire was heard in a car park outside a dormitory on the campus in Flagstaff.
The suspected gunman, 18-year-old Steven Jones, surrendered to officers, said police chief Greg Fowler.
President Barack Obama is due in Oregon later on Friday to meet victims of another deadly college shooting.
Last week a gunman killed nine people at Umpqua Community College before taking his own life in a shootout with police.
That tragedy has renewed the debate about the nation's gun laws, an issue that sharply divides the country.
Authorities do not know how the confrontation in the latest incident in Flagstaff began. All four victims and the gunman are students.
"This is not going to be a normal day at NAU," said the school's president, Rita Cheng. "Our hearts are heavy."
She called the incident "isolated" and "unprecedented". Classes are still on for Friday.
Representatives from the Delta Chi fraternity's national organisation said its members were involved in the confrontation but did not have information about the victims.
Maria Gonzalez, a student at Northern Arizona University, said that she initially thought that she was hearing fireworks.
"I was studying for an exam so I looked out the window and see two people running, and that's when I realised they weren't fireworks they were actually gunshots," she said.
"How am I supposed to feel safe where I'm learning?"
The Mountain View Hall dormitory where the shooting took place houses the "majority" of students participating in fraternities and sororities, according to theschool website.
Arizona law prohibits guns from being carried on campus, but they are permitted inside of a locked vehicle.
Arizona Senator John McCain released a statement to say that he is praying for all those "impacted by this terrible tragedy".