Scottish Deputy First Minister Nicola Sturgeon joined hundreds at Glasgow Cathedral yesterday to remember those killed and injured when a police helicopter crashed into a Glasgow pub on Friday night.

Emergency services continued with a complex recovery operation at the Clutha Vaults as air accident investigators began a probe into the cause.

Eight people are so far known to have died in the crash - including all three occupants of the helicopter and five others who were in the busy city-centre pub.

The first of the deceased to be named was Paisley's Gary Arthur who had been in the bar. Three other names were released last night, including PC Tony Collins, PC Kirsty Nelis and helicopter pilot Captain Dave Traill

Twelve people remained in hospital yesterday with serious injuries.

Witnesses described how the Eurocopter EC135, operated by Bond Air Services, dropped out of the sky and on to the roof of the pub "like a stone."

People in the bar were joined by passers-by as they formed a human chain to rescue unconscious victims in the immediate aftermath of the crash, which happened at about 10.25pm.

Grace MacLean, who was inside the pub at the time, said: "There was a ska band on in the pub just at the back and it was fairly busy ... there was like a 'whoosh' noise - there was no bang, there was no explosion ... someone started screaming and then the whole pub just filled with dust. You couldn't see anything, you couldn't breathe.

"It was a real testament to the people of Glasgow, everyone in that pub was shouting 'here's the door' - they were helping each other out."

Labour MP Jim Murphy said he saw a "pile of people clambering out" of the bar as he was driving past.

"I jumped out and tried to help. There were people with injuries. Bad gashes to the head. Some were unconscious. The helicopter was inside the pub. I could only get a yard or two inside. I helped carry people out," he said.

The area around the bar remains cordoned off as emergency services conduct a "rescue and recovery" operation.

Police Scotland chief constable Sir Stephen House said that the rescue operation will go on for many days yet.

He said: "It will not be a quick operation. It's very complicated and indeed dangerous.

"I pay tribute to those people from the emergency services who are working in and around the scene."