University police chief Gregory T. Fowler identified the shooter as 18-year-old Steven Jones and said he used a handgun in the shootings at about 1:20 a.m. Friday.
"This is not going to be a normal day at NAU," said school president Rita Cheng. "Our hearts are heavy."
She called it an isolated and unprecedented incident and said classes would go on as scheduled Friday.
The parking lot where the shooting happened is just outside Mountain View Hall dormitory on the Flagstaff campus, which provides housing for many of the campus' sororities and fraternities.
Iowa City, Iowa-based Delta Chi Fraternity said Delta Chi members were involved, but executive director Justin Sherman said in the statement that the organization doesn't have detailed information about the identity of the victims.
Freshman Cameron Sands, 18, said he had pledged a fraternity and was supposed to move into Mountain View Hall on Friday.
"It's crazy. You don't think this stuff happens. When I think of Flagstaff, I think safety," he said.
Sands, who did not sign up for text alerts from the university, said he learned of the shooting in a phone call from his mother.
The gate to the dorm's main entrance was closed Friday, and police had the surrounding area taped off.
Student Maria Gonzalez told The Associated Press that she at first suspected firecrackers.
"I was studying for an exam so I looked out the window and see two people running, and that's when I realized they weren't fireworks they were actually gunshots," she said.
Mountain View Hall is home to many of the campus' sororities and fraternities, according to the school's website.
Brown said the wounded were taken to Flagstaff Medical Center, which said it couldn't release any information on conditions.
Both university and Flagstaff police are investigating.
