Among the seriously injured are three more children. Hospital sources said their chances of survival are slim.

Most suffocated to death as the bus sank under several feet of sewage. Police are yet to ascertain if the mishap was due to rash driving or mechanical failure.

Locals who witnessed the accident said the overcrowded bus — plying on route 217B from Babughat to Narayanpur near Baguihati — was busy racing another bus, an usual practice on Kolkata roads that has claimed many lives. But today’s accident is probably the biggest in terms of loss of life.

Rash driving, though, was not the only thing responsible for the loss of lives. The rescue operation was in a shambles too, with no cranes available to pull out the bus from the canal.

Thousands of curious onlookers blocked the VIP Road, severely hampering rescue operation. There were few security personnel to cordon them off. Two cranes were used to retrieve the bus from the canal. The steel wire of one crane snapped delaying the rescue operation.

Still, the police managed to rescue at least 35 passengers with the help of the locals.

Prabhat Mishra, district magistrate, North 24 Parganas, said a 15-member divers’ team of the BSF’s 104 Battalion’s Disaster Management unit helped. Till late evening, they were scanning the canal waters.

While the driver’s fate is unknown, police said the conductor survived the mishap. The bodies of the deceased and the injured passengers were taken to several nursing homes in the area including Apex Nursing Home, Uma, Charnock Hospital and Swasti Nursing home.