LONDON (Reuters) - At least four people died when several vehicles including a truck crashed on one of Britain s main motorways on Saturday, police said. The collision took place around 2:30 p.m. (1330 GMT) in south Gloucestershire, prompting the motorway to be shut in both directions.  Sadly, at least four people have died,  Avon and Somerset Police said in a statement.  Major crashes involving multiple fatalities are relatively uncommon in Britain but eight people died in August when two trucks and a minibus collided at the start of a busy bank holiday weekend. 