A protester was shot and a man set on fire on Monday as protests in Hong Kong spilled into rare daytime hours, forcing public transport, offices and schools to shut down.

A 21-year-old activist was in critical condition after being shot and wounded at around 7.20am as traffic police trying to stop protesters from blocking a road fired three live shots with no prior warning.

Police later said all were meant to be warning shots, as the officers felt their lives were under threat. Video circulating online showed an officer holding a protester and pointing his gun at another, firing at close range.

Another man was admitted to hospital for burns, after he was set on fire. Videos online show protesters arguing with a man in a green t-shirt, as he criticises Hong Kong’s pro-democracy activists. A masked person in black then throws liquid over the man, and sets him on fire.

The violence is pushing Hong Kong to the “brink of no return,” said Hong Kong chief executive Carrie Lam. She condemned the protesters’ “wishful thinking” that escalating violence would force the government to meet their demands.