Police said a plainclothes officer was beaten up by a group of protesters and he fell to the ground.

In a statement, the force said he fired one shot in self-defence while facing a serious threat to his life. A rioter then threw a petrol bomb at him and his body was set on fire.

While trying to extinguish the flames, he dropped his pistol and magazine on the ground.

The force also said another protester tried to take the pistol and was stopped by the police officer. While waiting for reinforcements, another petrol bomb was thrown at the officer and his feet were set on fire. The officer was unable to pick up the dropped magazine when he retreated.

A 14-year-old protester, suffering leg injuries, was sent to Tuen Mun hospital for treatment. He’s reported to be in a serious condition. A bullet was found at the scene.

The police have appealed to members of the public to return any bullets or bullet casings they find, saying it’s an offence for any person to possess ammunition without a licence.