A man is undergoing surgery and three others are being treated in an Essex hospital after a crash on the A13 near Southend.
The four people were taken to Southend General Hospital after the accident which took place in the early hours of Saturday morning.
An Essex Police spokesman said that a silver Astra and a green Vauxhall Vectra travelling out of Southend were involved in a collision with two taxis heading in the opposite direction.
A silver Astra and a green Vauxhall Vectra travelling from the town were involved in a collision with two taxis heading in the opposite direction, at the junction of London Road.
Police are trying to trace a dark-coloured people carrier which left the scene soon afterwards.
It is thought there was an altercation between the occupants of the three cars shortly before the crash.
Police are also investigating whether the incident had any racial motive.