Two people have been killed in a motorway pile-up involving a horse box from the famous trainer Brian Meehan's stables.
A man has been arrested on suspicion of causing death by dangerous driving following the crash on the M11 near Harlow.
The trailer carrying five horses collided with three cars and a lorry shortly after 2.15pm in a smash that left the northbound carriageway closed between junctions seven and eight.
Essex Fire and Rescue said it had to free three people trapped in cars.
Two people in a car have died and the driver and passenger in another car have been taken to hospital in Cambridgeshire.
A woman has serious internal injuries and was flown by air ambulance and a man was taken by ambulance with a head injury.
It is not yet clear if they were hurt in the crash or if any of the animals will need to be put down, but the trainer's three intended runners at Newmarket on Thursday evening were withdrawn.
The road remains closed
More top news
Rain spreading north tonight and perhaps thundery at times, but a drier day tomorrow with minimum temperatures of 10 deg C
Organiser's of Peterborough's 33rd Truckfest say around 30,000 people have visited the event over the last two days.
The last set of constituency polls ahead of the General Election suggest a close battle in key marginals in the Anglia region.