The pyrotechnics, put on by the Taunton Rugby Football Club, finished about 10 minutes before the crash Friday evening and was less than a quarter of a mile from the M5 motorway in Somerset, The Daily Telegraph reported. The pileup killed seven people as trucks and cars slammed into each other, many of them bursting into flames.
"Our main line of inquiry has now moved toward the event that was on the side of the carriageway," Anthony Bangham, the assistant chief constable for Somerset and Avon, said.
Witnesses described a wall of fog on the motorway and some said they saw smoke. Mike Penning, the transport minister, said the witnesses could have been reporting smoke produced by the crash itself.
"Once these lorries caught fire, diesel produces a very black acrid smoke, the tires were alight, the plastics were alight," he said. "That mixing with mist or fog would create something that people might have thought was there before but was not there before but was part of the accident."
Tom Smith, an official with the British Pyrotechnists Association, told The Guardian wind would have blown any smoke produced by the fireworks away.
The dead include two truck drivers, and a wheelchair-bound man and his daughter who were driving home from a funeral. Another daughter was in an induced coma Monday, not realizing she had lost her father and sister, the Telegraph said.