Tucson (US): A failing US nursing student armed with two guns and possibly a bomb shot dead three of his professors and then apparently committed suicide, officials and witnesses said.

The rampage on October 28 marked the second high profile shooting in the United States since two men were arrested on October 24 and charged with a wave of deadly sniper attacks in the US capital that left 10 people dead.

The latest gunman, identified by police in the South Western US city of Tucson, as 41-year-old Gulf war veteran Robert Stewart Flores, was armed with two hand guns and may also have had explosives with him, police said.

Flores shot dead one of the teachers in her office at the University of Arizona nursing school, before going upstairs and mowing down two more in front of a class of about 30 students who were sitting a nursing exam.

"This was not a random act of violence," said Tucson police chief Richard Miranda, adding that the killings of associate professors Cheryl Mc Gaffic, 44, Barbara Monroe, 45 and Robin Rogers, 50, were pre-meditated.

Divorced father of two, Flores apparently killed himself following the attack, which took place at around 8 pm (IST), Miranda said.

Authorities suspected that the gunman might also have been carrying a bomb in a backpack found under his body or in his car, Miranda said.

"We had information that the suspect had (earlier) threatened to blow up the building and we called out our explosives people to evaluate that situation," he said adding that a bomb dog had detected possible traces of explosives in the gunman's car and backpack.

AFP