Hong Kong security forces shot an 18-year-old pro-democracy protester in the chest with a live round during a demonstration against China’s National Day celebrations. Video of the shooting captured by students protesting in the Tsuen Wan neighborhood shows the moment a police officer points a pistol at the black-clad protester and fires. The protester then falls to the floor. The shooting marks the first time police have used live ammunition against protesters, who have been demonstrating in the city for months. Police have previously fired live ammunition into the air to try to disperse crowds, but never at the protesters. Photos of the injured man calling for help and receiving medical care have also emerged on Facebook.

Police confirmed that an officer opened fire at a protester, but said the violent escalation was in self-defense. “A large group of rioters was attacking police officers in Tsuen Wan,” police said in a statement. “Police officers warned them, but they were still attacking police. A police officer’s life was seriously endangered. In order to save his and other officers’ lives, they fired at the attacker.” An official at the city’s Hong Kong Hospital Authority told Reuters the gunshot victim is in critical condition. At least 15 others were injured in the day’s running clashes and more than 50 people were arrested.