In a police briefing on Tuesday night, Kowloon East Superintendent Wu Ka-yan said that Chow likely fell between 12.45am and 1am but that his officers did not realise the accident happened until they saw firefighters applying first aid in the car park at 1.05am.

He said Chow might have thought that there was a ledge just below the third-floor wall that he had climbed over. Instead, he said, the student fell four metres (13 feet) onto the second floor.

Wu said police had launched several rounds of tear gas near the car park on Tong Chun Street before they found Chow, some 120 metres (390 feet) away.

Concerning rumours circulating online that Chow might have been pushed by police, Senior Superintendent Foo Yat-ting said there was no truth to the accusation.

She said that riot police had not obstructed nor interfered with any rescue efforts by ambulance and personnel from the fire department. The department also confirmed this to be the case.

And she said that police did not use any tear gas rounds or other projectiles inside the car park while clearing it from the ground floor. Police fired 44 tear gas rounds, 11 rubber bullets, three beanbag rounds and one sponge-tipped round in the vicinity during the dispersal.

As news of the student’s ailing condition gripped the city and well-wishers turned up at the hospital to offer prayers, Chief Executive Carrie Lam Cheng Yuet-ngor on Tuesday expressed her sympathy to Chow and others who were injured in protests over the weekend and hoped they would recover soon.

“[Chow’s] case requires investigation and we can’t make a conclusion now,” Lam said in Shanghai, where she was attending the second China International Import Expo.

“Police have attached high importance to this case and referred it to the crime squad for investigation.”

Sources had said overnight that Chow could not be saved and that removing him from life support was only a matter of time. Chow had two operations on Monday to remove part of his brain tissue and to stop the swelling in his head but separate sources said neither had helped to reduce the damage.

Tests to confirm brain death were not carried out on Tuesday.

Family members, friends, schoolmates and teachers of Chow flocked to the hospital’s intensive care unit on Tuesday.

“I don’t know him personally but I rushed here right after I saw articles saying his situation got worse in the afternoon,” said a student reporter from HKUST surnamed Wong, who was out of breath after running up the stairs at the hospital.

The university’s president Professor Wei Shyy and Professor Yeung Dit-yan, head of the computer science and engineering department, also went to the hospital.

About a dozen people, who did not know Chow personally, were taking turns to pray outside the intensive care unit throughout the day.

At the car park in Tseung Kwan O, friends of Chow had placed notes on parked cars, urging the owners to provide footage from dashboard cameras taken between 1am and 2am on Monday when the incident happened.

Link Reit, which owns the car park, said on Monday that CCTV footage had not captured the moment the student fell, as the camera rotated during its operation. Its view was also partly blocked by parked vehicles.

In a letter to university members, Shyy said he had contacted Link Reit to request the related CCTV footage. He also sent a letter to the police commissioner to ask for guidelines on how to protect oneself during protest situations, especially those involving tear gas.

While there were allegations that Chow fell while fleeing tear gas, the university’s campus radio station quoted witnesses saying that Chow had quarrelled with police on a bridge before falling during attempts to escape arrest.

A first-aider who helped treat Chow said he did not smell tear gas. He told a local TV station that riot police arrived about five minutes after he had begun administering first aid and pointed guns and batons at him, ordering him to leave. The Post was unable to verify these claims.

The fire service on Tuesday said that firefighters were focusing on their first aid and had not noticed any situation of police officers pointing guns at them or volunteer medics.

A forum will be held in HKUST on Wednesday afternoon, according to a separate letter sent from the president’s office to members of the university. The forum is to “continue the dialogue” between Shyy and students from a previous meeting held on Monday.

Protesters, who had gathered outside the car park from about 10pm, threw bricks at riot police who arrived about an hour later. Tear gas was fired at 11.08pm.