At least one person was killed and 32 have been hospitalized after a Scottish police helicopter plunged into a pub in Glasgow, security forces said Saturday.

Emergency service personnel were continuing their rescue efforts after Friday night's crash at The Clutha pub, located on the banks of the River Clyde.

"Given an incident of this scale we must all prepare ourselves for the likelihood of fatalities," First Minister of Scotland Alex Salmond said on Twitter before the death was reported.

The injured were taken to three area hospitals, while a team of 125 firefighters was working to make their way inside the pub and free those still trapped.

The assistant chief officer of the Scottish Fire and Rescue Service, Lewis Ramsay, said contact had been established with people inside the building, but it was difficult to know their exact number because the structure is very unstable.

Firefighters were working to prop up the one-story pub, whose roof had collapsed as a result of the impact, so they can get inside and rescue more victims trapped under the debris.

Scottish Police Service Deputy Chief Constable Rose Fitzpatrick said Saturday that an investigation was underway into the crash but that it was still too soon to provide details of why the helicopter plunged out of the sky.

The Eurocopter EC135 T2 police aircraft carrying two officers and a civilian pilot crashed into the roof of the pub - falling out of the sky "like a stone," according to one witness - when an estimated 120 people were inside, including the members of a ska band giving a concert.

Some people managed to rush into the street, but many others were trapped amid the rubble. EFE