A police helicopter crashed on the roof of a crowded Glasgow pub causing numerous casualties including probable deaths and many trapped.The crash occured on Friday night at around 10-30 p.m. local time.The pub,”Clutha” where more than 100 revellers had been listening to a band before the accident occured.Witnesses spoke of screams and a scene of horror,they saw the chopper dropping like a stone from the sky, while people inside the pub heard a whooshing sound before the roof caved in and the air filled with dust and screams.Police said there were two police officers and a civilian pilot on the crashed Eurocopter EC135 helicopter.