Three people have died after a police helicopter crashed into a busy pub in Glasgow, the BBC understands.

Police Scotland have confirmed one death but said they expected the final number of fatalities would be higher. A rescue operation is continuing.

The crash happened at The Clutha in Stockwell Street at 22:25 on Friday.

There were three people on board the helicopter - two officers and a civilian pilot. Thirty-two people have been taken to local hospitals.

Scotland's First Minister Alex Salmond told a press conference it was a "black day for Scotland."

Prime Minister David Cameron paid tribute to the bravery of the "ordinary Glaswegians" who rushed to help.

Chief Constable Sir Stephen House confirmed that one person had died and further fatalities were expected after the helicopter crashed on to the roof of the pub.

He said they "can't say definitively" whether there are people still trapped within the pub, and added "we are still in a search and recovery phase".

Chief Constable House went on: "This is a very difficult and sensitive operation. The scene is, as you will understand, a particularly challenging one.

"Given the damage caused and the nature of the damage, it will take some time to complete the search of the building and to assess how we begin the investigation.

"Clearly the safety of those conducting the search is of the highest importance."

Mr Salmond said: "This is a black day for Glasgow and Scotland but it is also St Andrew's Day and we can take pride in how we respond to adversity.

"The response from our emergency services and citizens has been exemplary."

It has been reported that about 120 people were in the pub at the time of the crash. Many were rescued or escaped but others were trapped by a collapse on the left-hand side of the building.

Emergency services have erected barriers around the scene and specialist rescue teams remain at the scene.

• A large area of the city centre has been cordoned off
• Mass held at St Andrew's Cathedral in city for those involved in crash and emergency services involved in response
• Council has cancelled St Andrew's Day celebrations in George Square as a mark of respect
• A minute's silence was held ahead of the Falkirk v Rangers match
• Injured were taken to Glasgow Royal Infirmary, Western Infirmary and the Victoria Infirmary
• Some of those who were in pub taken to a nearby Holiday Inn Express
• Police Scotland Casualty Bureau number is 0800 092 0410 - for those concerned about relatives
• Glasgow City Council has opened a family reception centre at 40 John Street
• Investigation into what happened is under way
• Air Accident Investigation Branch is in Glasgow.

Speaking from the press conference at the multi-agency command centre in Glasgow, Fire Scotland deputy chief officer Alex Clark said: "Along with our emergency service colleagues, we responded very, very quickly and pulled out all the measures that we possibly could in order to rescue people who were affected by this incident.

"I can assure you that until such time as there is an inevitable outcome we will undoubtedly remain on site and carry on our rescue activities in the best way that we possibly can."