A man died after his arm was severed in a minibus crash which left three other passengers seriously injured and 11 wounded.

The minibus was taking adults with learning difficulties northbound along the A23 when it smashed through the central reservation and overturned.

Eight people, three of whom were seriously injured, were taken to the Royal Sussex County Hospital in Brighton.

The man, believed to be in his 30s, died after being flown by helicopter to the East Surrey Hospital in Redhill but medics could not save his life.

Six people with minor injuries were taken to the Princess Royal Hospital in Haywards Heath.

The minibus was left lying on its side following the accident at 3.40pm yesterday, which happened on a notorious stretch of the busy road near Pycombe, just south of Albourne.

Motorists were caught in long tailbacks as drivers tried to make their way by alternative routes, clogging up roads in surrounding towns and villages.

Brighton fire officers who were first to arrive described the scene as "horrific".

A witness described seeing what was believed to have been the man's severed arm being recovered by paramedics.

The bus was carrying a group from London, called the Asian Parents' Association for Special Educational Needs in Tower Hamlets. The group had been on a day out to Brighton and were on their way home.

Darran Sampson, crew commander at Brighton's Preston Circus fire station, said members of the public including an off-duty fire-fighter from Eastbourne and a nurse pulled over to help.

He said: "We were the first crews on the scene. When we got there, there were multiple casualties on the road being treated by drivers.

"One man was trapped under the minibus. It was a horrific scene but it's what we are trained to deal with.

"There were no fatalities but everyone had injuries. There must have been about ten walking wounded."

The crash took place about a mile north of the stretch of road where eight people died in May 2004, and less than a mile from where a man died in April last year.

Salesman John Day, 42, from Worthing, was driving home from work on the A23 at the time of yesterday's accident.

He said: "I got there 30 or 40 seconds after it happened. The air ambulance came and took one person away who I think had lost his arm. I saw it put in a plastic bag."

The scene was attended by ten ambulance crews, Sussex Police and fire-fighters from West and East Sussex.

The man who lost his arm had to be cut out of the vehicle by firefighters before being airlifted to hospital by the Hotel 900 police ambulance helicopter from Shoreham.

Vehicles had to be diverted the wrong way up the northbound carriageway. Roads around Burgess Hill, Crawley, Ditchling and Poynings were gridlocked for hours by traffic coming off the A23.

In Tesco in Burgess Hill, staff handed out free bottles of water to customers stuck in their vehicles in the sun.

Police spokeswoman Elaine Koksvik said: "There has been serious road congestion and motorists have been warned to expect severe delays in the area."