Five of the victims were travelling in the same black BMW

A two-year-old boy and a woman travelling in a Land Rover Freelander were critically hurt in the crash and died in hospital on Monday.

The accident happened on the A23 at Pyecombe on Sunday at about 1630 BST.

Five of those killed were in a black BMW which had veered across the central reservation and struck the Freelander in which a male passenger also died.

This is the most serious incident in the area for many years Inspector Jon Brydon

Police said another person, who was in the Freelander, was still in a serious condition in hospital

Three others suffered minor injuries and were taken to hospital.

The victims in the BMW, three men and two women, were all thought to be in their 20s.

The collision happened at about 1630 BST while the roads were heavy with traffic heading away from the seaside resort.

The A23, the main road north out of Brighton, was closed all night in both directions, causing serious tailbacks.

It was re-opened at about 0745 BST on Monday.

The BMW struck a Land Rover Freelander

Two other vehicles were slightly damaged with their occupants receiving minor injuries.

Inspector Jon Brydon of Sussex Police's Road Policing Department said he was anxious to speak to anyone with information about the crash.

He said: "This is the most serious incident in the area for many years and we need to ensure that the examination is a thorough one.

"No matter how small the piece of information, we would ask that the public phone us as soon as possible so we can establish exactly what happened to cause this terrible tragedy."

A Sussex Ambulance spokeswoman said counselling was being offered to witnesses.