DHAKA: A police helicopter has crashed into a pub on the banks of the River Clyde in Glasgow.
The crash happened at The Clutha in Stockwell Street at 22:25, reports BBC.
Police Scotland confirmed there were three people on board. It has been reported that about 120 people were in the pub at the time.
There are thought to have been multiple casualties but it is not known if anyone has died. It is understood some people are trapped inside the pub.
Eyewitnesses have reported seeing the helicopter "falling like a stone".
Police Scotland
As he left the Accident and Emergency Department of Glasgow Royal Infirmary, a member of staff who did not want to be interviewed was asked how serious the injuries were. He replied with one word: "Very".
First Minister Alex Salmond said: "Given an incident of this scale we must all prepare ourselves for the likelihood of fatalities".
The emergency services could be seen on the roof of the pub trying to rescue people from inside. A large area of the city centre has been cordoned off.
The Scottish Fire and Rescue Service`s response includes a specialist urban search and rescue crew.
The BBC`s Scotland correspondent James Cook said rescuers were working "methodically" as they attempted to get people out safely.
Images of the crash showed the wreckage of a dark blue helicopter with a yellow "POLICE" insignia lying on the roof of the pub.
A police spokesman said: "Police Scotland can confirm that the service helicopter crashed earlier this evening in Glasgow city centre.
"A major incident has been declared after the Eurocopter EC135 T2 - with a crew of three consisting of two police officers and a civilian pilot - came down on the roof of a pub in Stockwell Street at 10.25pm.
"Emergency services responded immediately and remain at the scene at the present time.
"Cordons have been put in place to allow the rescue operation to take place.
"At present Police Scotland is not in a position to confirm any details regarding injuries".
Jim Murphy MP tells the BBC that "something horrific and serious happened"
The Police Roll of Honour Trust tweeted "Our thoughts are with the crew of @policescotland SP99 helicopter that has crashed in Glasgow - hoping everyone is alright."
Jim Murphy, the Labour MP for East Renfrewshire, said he ran into the pub to help before the emergency services arrived on the scene.
He told the BBC: "I was just a few yards away and I arrived on the scene outside the pub a few seconds after the impact. No-one knew what it was but you saw the pandemonium of the people trying to get out of the pub.
"It was almost like slow motion. Like other people you just do what you can to help."
Crash scene A police insignia could be seen on the wreckage of the helicopter
Mr Murphy, who is the shadow international development minister, said it was a "horrific scene". He added: "As you stood there you could see the helicopter embedded in the roof and sticking out the top of the roof and you knew it was something really serious."
Mr Murphy, who had blood on his shirt which he said was not his, said he did not see the crash happen and it was all a bit of a blur for a few minutes before the emergency services arrived.
He added: "People just formed a bit of human chain, side by side with each other, to help pull injured people out."
Eyewitness Fraser Gibson, 34, was inside the pub with his brother to see his former band, Esperanza.
"Midway through their set it sounded like a giant explosion," he told BBC Scotland.
"Part of the room was covered in dust. We didn`t know what had happened. We froze for a second; there was panic and then people trying to get out the door."
Mr Gibson said that immediately following the incident there was a suggestion that a helicopter had crashed into the roof of the pub.
Gordon Smart of the Scottish Sun: "I saw the whole thing happen"
"There was no obvious sign of that," he said. "I couldn`t hear of any rotors or anything like that before the event happened or any sign when we came out of the pub."
"I would say there was maybe 120 people inside the pub. A lot of people managed to get out straight away, but it was hard to tell how many were actually trapped in the other half of the bar.
"We wanted to get out of the way and let the emergency services get in there to help.
"I spoke to one of my former band members and he`s as much in the dark over the situation as me.
"We checked that each other was safe and the rest of the band were safe. The immediate group I was with are all safe.
"We`re obviously very concerned about what casualties have been sustained in the incident.
Scene of crash Emergency services vehicles at the scene
"There were no signs (of a helicopter) at all. The roof had just totally collapsed, there were shards of wood sticking out the top but nothing that said there had been a helicopter crash."
A Scottish Fire and Rescue Service spokesman said: "I can confirm that we have people at the scene.
"It is obviously a major incident. There are numerous fire engines there; 15 fire engines at the moment along with specialist services.
"I cannot confirm if there have been any injuries."
BBC Scotland reporter Andrew Kerr said: "I live nearby and actually heard the helicopter overhead just around that time and there was a definite change in the rotor noise and then there was just silence.
"I thought nothing more of it until I heard the sirens. The actual Police Scotland helicopter SP99 is based just two miles west along the River Clyde. It is well-known for the people of Glasgow to see, covering things like football matches in the city."
Claire Morris, who lives near the Clutha bar, told BBC News: "We heard this bang. We didn`t really know what had happened and then we heard people coming out and screaming.
"I wasn`t sure whether there had been an explosion. 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.
Map of the area The crash happened at a pub in the centre of Glasgow
First Minister Alex Salmond tweeted: "The emergency services are in full operation. Our thoughts are with everyone involved. Scottish resilience operation now mobilised."
Prime Minister David Cameron tweeted: "My thoughts are with everyone affected by the helicopter crash in Glasgow - and the emergency services working tonight."
In 2002, a police Eurocopter EC-135 came down in a field in Ayrshire. All three people on board survived.
In 1990, a police sergeant was killed when a Bell Jet 206 helicopter crashed in bad weather at Newton Mearns in East Renfrewshire.
BDST: 0830 HRS, NOV 39, 2013