According to WNBC :

NEW YORK -- A man was arrested for allegedly holding a student hostage with a gun on the C.U.N.Y. Harlem campus on Wednesday, according to a City College spokesperson.

After being tipped off, a security guard went over to the administration building to investigate reports of a man with a gun. When confronted, the man pulled out a black gun and held it to the head of a female student's head, a school spokesperson said.

Two police officers from the 26th precinct arrived on the scene moments later with guns drawn. The man released the hostage, put down the gun and was arrested by the police. No one was shot or injured, according to police.

A school spokesperson said another female student saw the gun in the man's backpack in the North Academic Center around 2:45 p.m. She went across the street and notified someone in the financial aid office, who then notified security.

Security called the police before investigating.

The suspect has been put under psychiatric evaluation at St. Luke's-Roosevelt Hospital Center, according to police