Dense smoke from a fireworks display is being investigated as the most likely cause of Friday\'s 34-vehicle pileup in the United Kingdom, in which at least seven people were killed, BBC said. Avon and Somerset Police Assistant Chief Constable Anthony Bangham said police were investigating smoke from fireworks as the \"major line of inquiry.\" He said the highway was covered by \"a bank of smoke\" when the deadly crash occurred. The crash took place on the at the M5 highway near Taunton, in south-west England, late on Friday. A total of 34 cars, including at least two trucks, collided. Eyewitnesses said \"a big ball of flames\" came from the vehicles in front. Television pictures showed chaotic scenes with cars and trucks ablaze and people desperately trying to rescue passengers trapped in the wreckage of their vehicles. Earlier reports said the accident could have been caused by heavy rain and fog.