A doctor has been shot at Johns Hopkins hospital in Baltimore and a suspect is holed up inside, police said.
A police department spokesman says the hospital is being evacuated.
He said he did not know the doctor’s condition.
A spokesman said officers were 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.
A spokesman for Johns Hopkins hospital in Baltimore earlier said the gunman had been caught, but police spokesman Anthony Guglielmi says that is not the case.
Mr Guglielmi says some parts of the hospital are being evacuated, but not the entire massive complex in east Baltimore.
With more than 30,000 employees, Johns Hopkins Medicine is among Maryland's largest private employers and the largest in Baltimore. The hospital has more than 1,000 beds and more than 1,700 full-time doctors.