Authorities in Glasgow, Scotland say a police helicopter crashed late Friday into a crowded pub during a concert, strewing debris over a wide area.
Local police did not immediately comment on casualties, but said they were dealing with a major incident. Witnesses said they believed some patrons may have been trapped inside the one-story building.
There were no signs of fire in photographs of the scene, and witnesses said there was no explosion. One photo showed the helicopter's propeller jutting from the rooftop.
Scotland's first minister, Alex Salmond, warned the public to prepare for the likelihood of fatalities.
British Prime Minister David Cameron, in a Twitter message, said his thoughts were with those affected by the crash.
Authorities say two police officers and a civilian pilot were aboard the helicopter.