Eyewitnesses told how smoke and dust filled the room as the roof plummeted to the ground after a police helicopter crashed into a pub while they were watching a gig.

Around 100 people were thought to be inside the Clutha, widely known as the Clutha Vaults, when the aircraft plunged into the roof, causing the ceiling above the bar area to collapse.

People inside the popular Glasgow bar did not initially appear to realise the severity of the situation and the band, Esperanza, continued to play. But smoke and dust quickly spread throughout the building as the debris scattered over people inside.

Fraser Gibson, an Evening Times sports journalist who was inside the bar at the time, said: "I felt an explosion from the other side of the bar and the roof just caved in."

Another eyewitness described hearing a loud crack before the roof collapsed on top of revellers.

Grace MacLean, who was inside the pub at the time of the crash, said: "It was fairly busy. We were all just having a nice time and then there was like a 'whoosh' noise - there was no bang, there was no explosion - and then there was some smoke, what seemed like smoke. The band were laughing and we were all joking that the band had made the roof come down.

"They carried on playing and then it started to come down more and 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."

Eyewitnesses were moved away from the area after the explosion and a large cordon was put in place as the rescue attempt continued inside the premises.

A message on Esperanza's Facebook page read: "Thanks for all the messages. I've just spoken to Jake and Jason. It seems that the band are all OK. Not so sure about everyone else."

Claire Morris, who lives near the bar, said she heard a bang before hearing people coming out of the pub screaming. "I wasn't sure whether there had been an explosion," she said. "My daughter said to me it was a helicopter that had hit the roof. Police are everywhere. We are just very shaken."

She added the pub was very popular and would have been busy on a Friday night.

"It was just a bang, my daughter said it was like a firework explosion, something like that. There doesn't appear to be a fire."

Jim Murphy MP, who was nearby at the time and helped in the rescue efforts in the immediate aftermath, said people formed a human chain to help pass unconscious people out of the pub so that "inch by inch, we could get the people out".

He said: "I think the building's only about 18ft, 20ft, tall so part of the helicopter is sticking out, but most of the helicopter is in the building."

Wesley Shearer, who was inside the bar at the time, tweeted: "The roof in The Clutha Bar just collapsed mid gig. People have been caught under it and smoke everywhere." He added later: "This is unbelievable. Just spent 20 minutes pulling people out of the bar."

Deputy First Minister Nicola Sturgeon tweeted: "Absolutely awful news about a helicopter crashing into the Clutha. All my thoughts are with everyone involved and the emergency services".