Trouble erupted on the Eastern Metropolitan Bypass on Sunday evening after a private car knocked down 14-year-old Anil Jha while he was trying to cross the road.
Additional superintendent of police Rajesh Singh said Jha was admitted to Ruby General Hospital, where his condition is stated to be critical. Residents blocked the Bypass and pelted stones at passing vehicles.
Three cars were damaged in the fracas as the mob demanded better policing of the accident-prone stretch.
The blockade was lifted after 8 pm, when senior police officers arrived on the spot and pacified the agitators. The car that knocked down Jha was located and the driver arrested.