Four shot dead at Arizona college

Students were evacuated from their classrooms

Four people have been killed in the United States in a shooting at the University of Arizona's school of nursing.

He lost his cool and ended up shooting the teachers numerous times

Eyewitness

The attacker, a disgruntled student, killed two female university teachers before turning a handgun on himself in a classroom.

A fourth victim was found in another part of the building, a university security official said. It is not clear whether the fourth victim was a member of staff.

A university official identified the gunman as a mature student who had failed a nursing class and was struggling in a critical care class.

Eyewitnesses told a local television station in Tucson that he became angry after he was prevented from taking some exams.

"He lost his cool and ended up shooting the teachers numerous times," an eyewitness said.

Student Mabel Alvarez-Thornhill was among about 30 students who were sitting an exam when the gunman walked into the classroom.

She told a local Tucson newspaper that the gunman was "calm and armed with extra clips [ammunition]".

She said that he told his victims to "make your peace with God".

Some reports describe the gunman was a Gulf War veteran.

One student who was in the same class as him last year described him as a "rude, obnoxious type of person".

Searching the scene

Tucson Police Chief Richard Miranda said officers suspected that the gunman may have been carrying a bomb in a backpack.

"We had information that the suspect had threatened to blow up the building and we called out our explosives people to evaluate that situation," he said.

The police chief added that a bomb dog had detected possible traces of explosives in the gunman's car.

The nursing college and nearby buildings were evacuated.

Police escorted groups of students and university staff in buses to another part of the campus.

Arizona University has about 34,000 students.