Police shot and critically wounded a 17-year-old boy who brought a gun to school and fired a bullet into a wall Monday.

The teen was hospitalized with life-threatening wounds, police said. No one else was hurt.

Police said they were trying to establish a motive for the incident, which took place in a third-floor science classroom at Lewis and Clark High School (search).

"He was angry at everything. He was making threats about everything," said Police Chief Roger Bragdon.

Police negotiated with the boy for about an hour and a half, then "at some point he just decided he was not going to talk anymore and got aggressive," Bragdon said. The boy pulled out the gun and officers shot him, the chief said.

Earlier, about 2,000 students and staff were evacuated from the school after the boy entered the classroom and fired a shot from the 9mm semiautomatic (search) into a wall, Bragdon said.

The boy ordered the teacher and at least three students to leave and sprayed the room full of retardant from fire extinguishers, Bragdon said.

Students were taken by bus to the Spokane Arena, where their parents were told to pick them up.

Schools in Spokane do not have metal detectors, school Superintendent Brian Benzel said. There are no plans to change that policy. School was to resume Tuesday.