Two teenage boys needed surgery and have been kept in hospital after being cut free from the crushed rear carriage of The Big One ride.

It's put me off going on things like that and will probably give me nightmares

Ali Akbar Rafsanjani, passenger

Twelve other people were injured and treated for whiplash after the two carriages collided on the world's tallest rollercoaster.

The crash happened at around 2030BST on Thursday at the station where people get on and off the ride.

David Cam, director and company secretary of the Pleasure Beach, said a full investigation was under way and the Health and Safety Executive had been informed.

Slow moving

"We know that one car was sitting in the brakes outside the station, we don't know why," he said.

"We do have a completely automated computer-controlled system which gives us the advantage of being able to download details of the braking system so we can find out precisely what happened in those seconds before the accident."

David Cam hopes the investigation will discover the cause of the crash

Mr Cam said the cars were only travelling at two or three miles per hour when the accident happened.

The top speed of the ride is 87mph.

Mr Cam said that safety continued to be of the "highest possible standard" as it had been over the last 104 years of the Pleasure Beach's history.

Second accident

But the accident follows the death of 11-year-old Christopher Sherratt who fell from the Space Invaders ride at the Pleasure Beach in July.

Mr Cam said the two accidents were unrelated and there was no mechanical failure in the Space Invaders incident.

I was knocked out for a few seconds, and when I came to there was panic all around

Injured Ali Akbar Rafsanjani

The two injured boys, aged 13 and 15 years, were from a children's home at the resort and had been accompanied by social workers on the ride.

Duty manager at Blackpool's Victoria Hospital, David Wells, said they received people with a mixture of fractures and dislocations who were expected to be kept in for the foreseeable future.

Glen Curry, a spokeswoman for Lancashire Ambulance Service, said most of the people who got off the train were walking wounded.

Ride closed

Passengers on the second rollercoaster said they knew there was going to be a problem.

Kate Black, 18, from Liverpool, said: "We were aware that there was going to be a problem as soon as we set off because the other rollercoaster seemed to be stuck, but we didn't think it would be a serious thing."

Ali Akbar Rafsanjani, 26, from Bradford, was treated in hospital for whiplash injuries after he blacked out during the collision.

"I remember being on the ride going round and then all of a sudden when we came to a halt there was a big bang and smash in the back," he said.

"There were screams. I was knocked out for a few seconds, and when I came to there was panic all around. It was chaos, it was really frightening.

"It's put me off going on things like that and will probably give me nightmares. You think the safety measures are OK and then something like this happens."

The Big One ride will be closed until the investigation has been completed but the Pleasure Beach will be open as usual on Friday for visitors wanting to see the famous illuminations switched on by boy band Westlife.