A Class V student is battling for his life after falling off a bus and being struck by an autorickshaw overtaking from the left when he and some passengers were boarding the vehicle in the middle of the Park Circus connector.

Mohammad Shoaib, 11, was flung a few feet on impact and became unconscious after the fall. The bus didn't stop and neither did the autorickshaw. Some pedestrians and a man who was taking his son to school on his motorbike moved Shoaib to Calcutta National Medical College and Hospital, from where he was shifted to Apollo Gleneagles Hospitals and again to a hospital in Bagbazar.

An official at Apollo's emergency department described the boy's condition as critical. "He had been put on ventilator support but his family decided to shift him to another hospital," the official said.

Shoaib, a resident of Topsia, was boarding the bus to reach his school in Beniapukur on Monday morning when the accident occurred.

Mohammad Sirajuddin, who was passing by, saw Shoaib being knocked down by the autorickshaw the moment he fell. Police sources said it wasn't clear how he lost his balance but eyewitness accounts did confirm that the bus was nowhere near the side of the left lane when it was picking up passengers.

Sirajuddin, who requested another parent to escort his son to school so that he could move Shoaib to hospital, said both the bus and the autorickshaw were at fault.

"The boy wouldn't have gone to the middle of the road to board the bus had the driver steered to the side of the left lane to pick up passengers. The autorickshaw was speeding and, to make it worse, overtaking from the left," said Sirajuddin, whose son is a Class VIII student at The Frank Anthony Public School in Beniapukur.

"Almost all autos are guilty of speeding and zig-zagging their way through traffic but the police don't do anything about it," Sirajuddin rued.

Shoaib was bleeding from his ears when Sirajuddin and some others lifted the boy into an app cab. A few taxis and autorickshaws had refused to take the injured boy to hospital but the driver of the app cab volunteered to help, he said.

An older boy who studies in the same school as Shoaib and was on the bus when the accident occurred reported the incident to his headmaster. "The boy told me that the bus conductor forced all passengers to get off near Ghasbagan, the stop next to the Hindu Burial Ground. The empty bus sped away," said Mohammad Khaled Reza, headmaster of Islamia High School.

The boy confirmed the route number as KB-21 but could not note down the registration number of the vehicle. He had boarded the bus at the Hindu Burial Ground stop, where Shoaib too had been waiting for transport.

Shoaib had joined Islamia High School only seven months ago. His father owns a shop selling utensils at Kohinoor Market in Topsia.

Neighbours of the family said they didn't have medical insurance or cash to cover the cost of Shoaib's treatment at Apollo Gleneagles, which is why they shifted him to a north Calcutta hospital.

The police have started a case against the unidentified bus driver for "rash driving and causing grievous hurt by act endangering life or personal safety of others". A police officer said it would be difficult to confirm how Shoaib fell off the bus since the location where it happened does not have CCTV cameras.

Buses stopping or merely slowing down in the middle of the road are, of course, common in Calcutta and nobody bats an eyelid until a tragedy happens. The absence of proper bus stops and inadequate public transport often compel commuters to board or get off buses at risk to life and limb.