A government bus that should not have been on the road overturned on the Park Circus connector on Tuesday morning, injuring at least 14 passengers. The accident occurred near the Viswakarma building, close to the intersection of Topsia Road and the connector, around 8.15am.

Doctors at Calcutta National Medical College and Hospital said some of the injured were treated and discharged, but six — including the bus driver and conductor — remained in critical condition with multiple injuries.

Eyewitnesses told police that the bus — travelling from Howrah to Kamalgazi — suddenly swerved to the right near the Topsia Road intersection and crashed into the iron divider under the Parama flyover. A front tyre burst on impact.

“We heard an explosion, turned back and saw the bus overturned. Some of us were waiting at the stop,” said a young man at the scene. “Immediately, people ran towards the bus.”

With passengers trapped inside, bystanders broke the rear glass pane to help evacuate those inside.

The injured include the driver, Bapi Das, 37, and conductor, Sanjib Ghosh, 40, along with Mohammad Raja, 50, of Topsia; Bimal Poddar, 45, of Entally; Rajanya Dey, 20, of Salkia; and Sheikh Santu, 34, of East Burdwan.

Preliminary police investigation revealed that the bus was unfit to be on the road. Its fitness certificate had expired in September 2017 — nearly nine years ago. The vehicle also lacked a valid pollution certificate, which lapsed on July 31, 2024, sources in the transport department said. The bus was registered with the Howrah regional transport office on October 1, 2015, with its registration valid only until September 30, 2017. According to records, the bus is listed as a “Government Undertaking” vehicle.

“A bus cannot operate legally without a fitness certificate because it must meet the required safety and emission norms,” said a senior transport official.

A senior police officer said that operating a commercial vehicle without a valid fitness certificate carries a fine of ₹10,000 for a first offence.

When asked how such a bus was allowed to run, a transport department official said: “We will ask the West Bengal Transport Corporation (WBTC) for the details and check how it was allowed to run when it should have been in a garage.”

Calls to Abishek Churasiya, managing director of WBTC, went unanswered. Senior officials said that the state transport leadership was preoccupied with the Ganga Sagar Mela.

The accident caused traffic disruption along the Park Circus connector during the morning peak hour. Rows of vehicles heading towards EM Bypass were stranded until the overturned bus was removed by a crane. Smashed iron railings from the median divider were also cleared from the spot.

A case of rash and negligent driving has been registered at Topsia police station.