Essex Police were called to the scene of the crash on Monday at around 6.15pm. The incident occurred just outside Waltham Abbey and the carriageway remains closed between Junctions 27 and 26.
Two drivers have been arrested on suspicion of causing death by dangerous driving and on suspicion of causing serious injury by dangerous driving.
Police are keen to trace the movements of all three vehicles – a Mondeo, a minibus and a lorry – leading up to the collision.
Detective Sergeant Steve Holmes, from our Serious Collision Investigation Unit, spoke from the scene.
He said: “This evening has been incredibly challenging and we are continuing to work as quickly as we can to piece together exactly what led to this tragic incident.
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“My thoughts, and those of all officers on scene are with the families of those who lost their lives this evening.
“At present, two drivers have been arrested on suspicion of causing death by dangerous driving and on suspicion of causing serious injury by dangerous driving.
“I need anyone with further information to come forward.
“The road has remain closed whilst our colleagues tended to those who were injured and whilst we have gathered evidence and preserved the crime scene.
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“I would like to thank everyone on the M25 for their patience – I know it’s been a long night, and our colleagues in Highways England are aiming to get you off of the motorway by 2am.
“Please make sure you get home safely and, if you have any information at all that can help us, don’t hesitate to report it.”
People can report information online or on 101 and citing incident 972 of Monday, August 23.
Family members have yet to be informed of the tragic incident.