Image copyright Leah Washington Image caption Leah Washington was on the Smiler ride with her boyfriend

A 17-year-old girl injured in a rollercoaster crash at Alton Towers has had her leg amputated, it has emerged.

Leah Washington was on the front row of the Smiler ride, which crashed into an empty carriage in front of it.

Three others who were also in the front row sustained serious leg injuries, while a fifth person is being treated for internal injuries.

The theme park reopened on Monday and bosses said they would ensure the injured would be compensated.

The ride remains closed.

Ms Washington's father, David Washington, from Barnsley, said: "Leah has suffered a life-changing injury and now has many months of rehabilitation ahead of her."

Her leg was amputated above the left knee and she also suffered a fractured left hand.

Media playback is unsupported on your device Media caption The BBC's Jon Kay speaks to some of the first visitors to Alton Towers since it reopened

Image copyright facebook photos Image caption (L to r) Daniel Thorpe, Vicky Balch, Joe Pugh and Leah Washington are being treated in hospital

Ms Washington's boyfriend, 18-year-old Joe Pugh, from Barnsley, also remains at Royal Stoke Hospital where he is being treated for two broken knees and "extensive" hand injuries, a hospital spokesperson said.

Vicky Balch, from Leyland in Lancashire, who turned 20 while in Royal Stoke Hospital, has undergone surgery and is in a "serious but stable" condition, according to her family.

Daniel Thorpe, 27, from Buxton, Derbyshire, was treated at University Hospital Coventry for a collapsed lung and a fractured leg. His condition is described as "serious but stable".

Chanda Chauhan, 49, from Wednesbury in the Black Country, who was sitting in the second row of the Smiler, was admitted to Walsall Manor Hospital with internal injuries.

She had surgery to her stomach and has a damaged liver and blood clots, her daughter said.

Amir Khan, medical director at Walsall Healthcare NHS Trust, confirmed she had undergone surgery.

"She is now recovering in hospital," he said.

Image copyright PA Image caption The Smiler, Oblivion, Enterprise and Sonic Spinball rides at Alton Towers remain closed

Image copyright PA Image caption Julie and Paul Thornton, Lorna Bird and Alex Wells said they had been looking forward to their day out

In a statement, Alton Towers said it had written to all 16 of the injured or their families.

It said: "Irrespective of the outcome of the current investigations into the causes of the accident, in these letters we have accepted full responsibility to those who had been injured in the accident and confirmed that we will ensure that compensation will be provided to them.

"We have recommended each of the injured guests or their families instruct a lawyer and submit a claim for compensation which we will ensure is dealt with swiftly and sensitively."

Lawyers acting for Ms Balch, Ms Washington and Mr Pugh said they were "pleased" with the admission of liability.

Paul Paxton, from Stewarts Law, said he would be meeting Merlin's solicitors to discuss the "early release" of money to assist with financial hardship and rehabilitation.

Reports on Monday indicated crowds had been "steady if modest" at the attraction, with guests paying full price at the turnstiles, although the park has said it will not release any figures.

Dan Bennett, 35, visiting the park with his twin brother Matt, said: "We're not concerned. They wouldn't have opened the park if it wasn't safe."

Image copyright PA Image caption Dan Bennett (far right) said he was not worried about safety

"Accidents do happen and that's exactly what I think it was," said Matt Bennett.

Nina Lancaster and Daniella Dobson, from Leeds, took their 15-year-old daughters Jo and Sophie to the park, after booking their tickets a month ago.

"We wanted to come, and the girls were really excited when they found out yesterday that it would open today," said Mrs Lancaster, who told the girls "they can't go on the front or the back".

Image copyright PA Image caption Daniella and Jo Dobson, and Sophie and Nina Lancaster, said they bought their tickets a month ago

Mrs Dobson said she was more cautious about coming, but took the view safety precautions would be at their highest today of all days.

Owners Merlin Entertainments said it had carried out "a thorough review" of safety procedures.

Health and Safety Executive (HSE) inspectors have also been on site.

Image caption Alton Towers reopened at 10:00 BST, six days after the crash

Media playback is unsupported on your device Media caption Alton Towers customers have returned to the park

From the scene: Trystan Jones, BBC News Online

The queues at the entrance to Alton Towers could be measured in the dozens, rather than hundreds soon after the gates opened.

The car parks also looked pretty empty, although it was early in the day. Nobody I spoke to was worried about safety and a couple said they would be happy to ride the Smiler if it had been open.

One couple told me there was far more chance of having an accident on the way to the park than at it.

I spoke to two visitors who used to work at the park. They said safety was really strict, with operators having to complete hours of training before being allowed to operate rides. On some rides operators even have to complete written exams, they said.

Image caption The area around the Smiler rollercoaster remains fenced off

A number of people who had pre-booked tickets for Monday said they had chosen not to attend.

Student Louise Riley, who had planned to visit Alton Towers with a group of friends, said they did not want to feel "like guinea pigs" on the first day the venue has been open since the accident.

"We're quite a bit nervous that other rides have been closed as well," she said. "It makes you question the safety of all the rides."

BBC correspondent Peter Wilson spoke to 26-year-old Meera Singh, who was sitting in the second row of the Smiler at the time of the crash, with her 49-year-old mother Chanda and her 29-year-old sister Vanisha.

"Meera said what they witnessed that day they will never forget for the rest of their lives," he said.

"Amazingly, they just got into a taxi after being cut out of the Smiler, as they just wanted to go home.

"She said the family just felt lucky to be alive."

Later Chanda Singh underwent surgery for her injuries.

Image copyright Other Image caption The Smiler, Dragonsfury, Rattlesnake and Saw (clockwise from top left) have been closed

Merlin Entertainments chief executive Nick Varney said Tuesday's crash was the first accident in the company's history and it had introduced extra safety measures at its theme parks.

Mr Varney said Tuesday's crash had been "a terrible event for everyone involved".

The park "closed immediately" afterwards, he added, to allow preliminary investigations and give staff "time to come to terms with the [crash] and its aftermath".

"Alton Towers has a long record of safe operation and as we reopen, we are committed to ensuring that the public can again visit us with confidence."

The attraction has said anyone with pre-booked tickets is entitled to a full refund if they do not want to visit.

Media playback is unsupported on your device Media caption Honeymooner Craig Cooper: "It was horrific what happened but I'm glad they've opened the rest of Alton Towers."

Last week, a number of bed and breakfasts in the nearby village of Alton said people had cancelled bookings in the wake of the crash.

Janet Gibson from the Bull's Head Inn said business "has been tough".

"There were three days last week when the phone didn't ring and it's usually constantly going, especially when the weather's nice.

"We can only hope trade picks up now."

Others said the news that the park was reopening had prompted visitors to get in touch and they were "fairly full" for the next few weeks.

The X-Sector of the theme park - which houses the Smiler, Enterprise and Oblivion rides - will remain shut until further notice, as part of the HSE investigation.

The Spinball ride will also be closed until enhanced safety protocols have been implemented.

Image copyright WMAS Image caption The carriage was travelling at 20mph when it crashed

Mr Varney said the design of the ride meant it would take slightly longer than had been hoped for new procedures to be put in place.

Two rides currently closed at Merlin-owned Thorpe Park and Chessington World of Adventures, both in Surrey, are expected to reopen soon.

A prohibition notice has been served which prevents the Smiler being operated until "action is taken to deal with the cause of the failure".

It does not affect other rides at the park.

The two carriages that collided have been removed by the HSE to be examined in a laboratory.