O'Donnell said the state police received a call from the state-run chronic-disease hospital at about 8:15 p.m. about suspicious activity, flickering lights, in an abandoned building on the hospital grounds. A hospital dispatcher told the state police that the hospital had already contacted its own security company, Industrial Security Investigations of North Providence, and the Burrillville police.

About eight minutes later, the hospital called the state police again to report that a gun had been fired.

Security guard Brown said that he went into the building, where he got into an altercation with a man, according to O'Donnell.

The guard told the police that the man fell down a small set of stairs, then came back up toward him with what appeared to be a rusty knife, the state police said. The security guard said he fired once at the man, who then ran away, O'Donnell said.

While the state police don't believe the man was struck, they have contacted area hospitals to see if anyone sought treatment of a gunshot wound, O'Donnell said.

The state police are looking for the man, who is described as being about 6 feet tall, slender with no facial hair. He was wearing dark jeans, a gray hooded sweatshirt and white, dirty sneakers.