AlHijjah 9, 1432, Nov 5, 2011, SPA -- At least seven people were killed and 51 injured in a 34-vehicle pile-up on a British motorway in heavy fog, police said Saturday. Police said that death toll might still rise further as the burned-out wreckage was searched. The crash on Friday night on the M5 in Somerset, west England, included several heavy lorries, and was "the worst road traffic collision any one can remember" according to emergency workers, the Press Association reported. Assistant chief constable Anthony Bangham said a number of passengers were unable to escape from their burning cars. "The incident was very, very challenging and on arrival crews were faced with literally one massive fireball. " The motorway remained closed Saturday, with plans to reopen late in the evening. Meanwhile a huge task force of police, fire and ambulance crews were at work scouring through the wreckage. Police said the pile-up occurred during fog and heavy rain. The crash appears to be the worst in Britain since 1991.