A gunman opened fire inside one of the buildings at Baltimore's Johns Hopkins Hospital, where at least one doctor was reported shot.

Baltimore police say they're setting up a tactical operation to deal with a gunman who is holed up on the eighth floor of Johns Hopkins hospital after shooting a doctor.
(ABC News)The gunman, who has not been identified, is not in custody but has been "isolated" in a particular area of the hospital, according to Baltimore Police.

"We are in the process of getting the suspects, it's possible he is barricaded in a room," said Anthony Guglielmi, chief of public affairs for the Baltimore Police Department.

Guglielmi said that the doctor is in surgery but his injuries are not critical.

"The doctor is going to be OK – he's in the best place in the world," he said.

In the initial confusion, some reports said the shooter had been subdued, while others said police were trying to get a negotiator close enough to talk with him.