Armed police were called to an incident at Christchurch Hospital this morning.
An eyewitness says a man entered the hospital outpatients building about 10.30am and allegedly threatened to shoot someone.
A police spokesperson said they received a report of a person with a gun at the outpatient building.
Officers responded and determined there was no firearm involved, the spokesperson said.
One person has been arrested.
Canterbury District Health Board chief executive Dr Peter Bramley said police were called to an incident involving a patient at the outpatients building earlier this morning.
The incident has now been resolved and roadblocks are no longer in place.
Patients should attend their appointments on the Christchurch Hospital campus as planned, he said.
