A state bus knocked down three newspaper hawkers on Chittaranjan Avenue, near Chandni Chowk, early on Friday. In retaliation, local residents set a CSTC bus on fire and damaged three other state buses.

Three fire tenders were sent to the spot to douse the blaze. Four men were arrested for vandalism. The hawkers were taken to hospital, where their condition is critical.

Police said an SBSTC bus, headed for Shyambazar, hit the hawkers around 5.30 am. “The driver lost control and veered to the left, hitting Animesh Saha, Amit Shaw and Imtiaz Hussain,” said Pradip Chatterjee, deputy commissioner of police (headquarters).