At least two people were killed when a helicopter crashed into a crane at the top of a skyscraper in central London during rush hour today. The helicopter "plummeted straight into the ground," a witness tells the BBC. "The building the helicopter hit is shrouded in mist." Video footage shot by witnesses shows a street just south of the River Thames blocked by wreckage and burning fuel. Offices around the site of the accident are being evacuated because the crane is now in a "precarious position," the Guardian reports.