Two men have been arrested on suspicion of arson and attempted murder after another two were found with burns in east London.
One of the victims is fighting for life for the incident by the southbound side of the A406 in Ilford at around 11.45pm last night.
The other man's injuries are deemed not to be life-threatening.
A Scotland Yard spokesman said: "Both have been taken to an east London hospital. One remains in a critical condition; the second man’s injuries are not thought to be life threatening.
"Two other men – no further details – have been arrested on suspicion of arson and attempted murder; both remain in custody at an east London police station."
The London Fire Brigade dealt with the fire and the London Ambulance Service also attended.
The southbound carriageway of the A406 in Ilford remains closed.
Enquiries into the circumstances are ongoing.
