Several people were killed and dozens of others injured following a horrific motorway pile-up which triggered a "massive fireball" on the carriageway.
Around 27 vehicles, including a number of articulated lorries, were involved in the devastating crash, described by emergency workers as "the worst road traffic collision anyone can remember".
Avon and Somerset Police said "some" people lost their lives and around 51 people were injured in the tragedy, which happened in wet and foggy conditions on the M5 in Somerset last night.
Assistant Chief Constable Anthony Bangham said a number of passengers were unable to escape from their burning cars, some of which were razed to the ground.
"At around 8.25pm yesterday there was a multiple collision around junction 25 of the northbound carriageway of the M5," he said.
"This involved a large number of cars and also articulated lorries and up to about 27 vehicles in total.
"The accident resulted in a large number of casualties.
"Up to 35 people were injured - some of those seriously - and tragically a number have lost their lives as a result."
The officer continued: "The emergency services have been working tirelessly. The incident was very, very challenging and on arrival crews were faced with literally one massive fireball.
"Most vehicles were well alight and most continued to burn for a considerable time. This made it very difficult to search the vehicles. Some of them have been burned to the ground."
A huge taskforce of police, fire and ambulance crews were called to the stricken stretch of the M5, which was immediately closed off in both directions and remains shut.
Firefighters who scrambled around 15 appliances to the scene battled to rescue motorists by cutting people from cars and lorries using hydraulic equipment. Television footage also showed motorists trying to pry open vehicle doors in a bid to rescue those trapped.
The devastating road accident is believed to be one of the worst in the UK for 20 years.
Paul Slaven, of Devon and Somerset Fire and Rescue Service told the BBC: "This is the worst road traffic collision anyone can remember... so many vehicles involved."
Edmund King, president of the AA, said the scale of the crash was similar to one on the M4 near Hungerford in Berkshire in 1991.