M1 crash: Man arrested after two killed
A 25-year-old man has been arrested on suspicion of causing death by dangerous driving after two men were killed in a crash on the M1 in Hertfordshire.
The men, aged 22 and 24 and from London, died in the collision, involving two BMWs, between junctions 5 and 4 near Watford, at about 02:40 GMT.
Two other men were taken to St Mary's Hospital, London, with "serious injuries" police said.
The four men in the second car were also injured and taken to hospital.
A police spokeswoman said their injuries were not thought to be life-threatening. The arrested man is from east London.
A man living near the accident told the BBC he was awoken by the noise of the crash and when he got to the site he saw some survivors fighting.
Insp Paul Campbell of Hertfordshire Police said: "There were a number of people who clearly were suffering an emotive reaction to a very traumatic situation.
"To say they were fighting I could not clarify at this point in time."
The accident resulted in the closure of five junctions of the motorway in both directions.
The southbound carriageway remained closed for several hours as the Highways Agency repaired the crash barrier. The motorway fully reopened at about 12:45 GMT.
An investigation is now under way into the cause of the crash.
Police said they were not releasing any further details about the people who died until formal identification had taken place. They have appealed for witnesses.