Police have arrested a college student who walked around on his school's campus carrying a single-shot rifle and wearing a Bush rubber mask, police said.

No injuries were reported in the incident at St. John's University on Wednesday. It was unclear "why on this particular day he brought a gun on campus," police spokesman Paul Browne said.

Police identified the student as Omesh Hiraman, 22, and said charges were pending. St. John's is a Catholic university of about 20,000 students located in the city's Queens borough.

Other students, one of them a police cadet, reported seeing the armed man at around 2:30 p.m. walking near a building on the campus around the time he was supposed to be in a business class there, police said. The man was carrying a plastic bag with the barrel of a .50-caliber rifle sticking out and was wearing the Bush mask, with its mouth cut out.

In a statement, Police Commissioner Raymond Kelly praised the cadet, 21-year-old Christopher Benson. Benson said he saw a man with a gun "walking really fast" and "jumped right in" to assist when campus security officers approached.

Unarmed campus security officers and the student cadet tackled Hiraman as he walked toward a library, police said. Hiraman was turned over to the New York Police Department, which later searched his home near the campus.

The rifle was loaded with one bullet, police said.

Hiraman's father, Pat Hiraman, said the incident was "a misunderstanding" and his son, who lives at home near the school, "would never harm anyone."

"Our son has always been a good boy and has never been in any sort of trouble," the father said.

He said his son hadn't been the same since having back surgery and was under heavy medication.

Students were told to stay inside their classrooms and buildings until around 5:30 p.m. Classes on the campus were canceled for the evening.

Kevin Su, an editor of the student newspaper, said students were ushered into buildings that were staffed with security guards and told to stay put. He said there was not much discussion of whether there were similarities between the incident Wednesday and the April 16 rampage on the campus of Virginia Tech, where a student gunman killed 32 people and then himself.

"I think it's basically on everyone's mind," Su said. "It doesn't need to be said outright."