At least 22 people have been killed after a gunman went on the rampage at a US college campus.The dead are believed to be mostly students at Virginia Tech in Blacksburg, a state university known for its demanding science and engineering curriculum.Some reports have said around 32 people may have been killed.The gunman - who was said by witnesses to have been carrying a large amount of ammunition - was also killed although police have not confirmed if he turned a gun on himself or was shot by marksmen.The first reports of an incident came at around 7.15am (1115 GMT) in West Ambler Johnston Hall, a dormitory housing some 900 students. Most of the shootings occurred at another campus building, Norris Hall.College president Charles Steger said: "It's a monumental tragedy that leaves us horrified." President George W Bush also said he is "horrified" at the news.Virginia Tech houses 26,000 students and is located in the southwest corner of the state near Roanoke. The university has cancelled classes and asked students to stay inside, lock their doors and stay away from windows.It is one of the worst shootings on a US university campus since Charles Whitman went to the top of the tower in the middle of the University of Texas campus in Austin, Texas in August 1966 and opened fire on people 27 storeys below, killing 13 after killing his wife and mother the previous evening.Last October, five Amish schoolchildren were killed when Charles Roberts shot at ten girls at their school in Lancaster County, Pennsylvania.© Independent Television News Limited 2007. All rights reserved.