A constable from the elite Airport Security Unit accidentally discharged his gun at the airport police station yesterday.
Police are investigating whether the 28-year-old officer failed to follow proper procedure by handling his 9mm Glock 17 pistol in an unauthorised area.
"Disciplinary action will be taken against the officer if he is proven to have made a mistake and failed to follow guidelines over the use of firearms," a police source said.
The constable has not been suspended from duty, but has been assigned indoor work until the investigation is completed.
Officers from the Airport Security Unit each carry more than 13kg of weapons as they patrol Chek Lap Kok airport. More than 100 officers apply to join the unit each year. Fewer than 10 succeed.
Yesterday's incident happened at about 11.30am when the constable was alone in the station's changing room on Catering Road West, Lantau Island.
"As he was trying to change to a new holster, he pulled his gun out of the old holster and accidentally pressed the trigger," a police investigator said.
"One shot was fired, damaging a floor tile. The officer was unhurt," he added.
Crime-squad officers from the airport police station are investigating. The pistol has been handed to the forensic firearms examination division to check whether it malfunctioned.
There are strict guidelines for officers over the safekeeping and use of firearms. A police spokeswoman said that appropriate action would be taken if misconduct was proven.
In November, a pistol went off when a station sergeant tripped and fell to the floor inside a police post at the Airport Express station in Central. The sergeant was unhurt.
In July, a veteran officer escaped injury when he fired his pistol by accident at a Marine Police base on Stonecutters Island. And in February, a constable accidentally discharged his revolver at Kwai Chung police station when he was loading the gun. He was also uninjured.