(CNN) -- At least four people were injured when a school bus collided with an SUV Monday in Surprise, Arizona, according to officials.
One person in the SUV suffered life-threatening injuries and was flown to an area hospital, said Surprise Fire Captain John Klidas.
All three people on board the bus -- the driver, a school aid and a 15-year-old -- were taken to area hospitals with minor injuries, Klidas said.
Sgt. Mark Ortega, a police spokesman, said the crash happened shortly before 7 a.m. According to witness statements, a black Chevy Blazer swerved out of its lane and collided with the bus head on, he said. The bus then ran into the wall of an adjacent home, Ortega added.
He said the 23-year-old driver of the SUV suffered some broken bones, but that his condition has been upgraded to guarded from critical.
The cause of the accident is not known and under investigation, police said.