Two young boys remain in a serious condition in hospital after a roller coaster derailed at a Scottish theme park.

Ten people were taken to hospital after the carriage came off the rails on the Tsunami coaster at M&D's in North Lanarkshire on Sunday.

Five gondolas appear to have derailed as they were rounding a bend and plunged to the ground, trapping their riders.

Police working on the investigation into the incident on Tuesday set up a dedicated email address for witnesses to send pictures and footage of the crash. The address is rollercoaster@scotland.pnn.police.uk.

A statement said: "Police continue to appeal to anyone who was within the park during the time of the incident and who may have footage or images, either on mobile phones or cameras, to send them directly to the dedicated inbox."

Liam Boyle, 11, underwent surgery to save his badly injured hand. His grandfather, Thomas Campbell, from Glasgow, said on Facebook: "The good news is Liam's operation has been a success.

"They have saved his arm and hand. Recovery will take a while but at least we know he's going to be alright. Thanks for all the support, much appreciated."

Meanwhile, a 12-year-old boy with chest, abdominal and leg injuries also remains in a serious condition at the Royal Hospital for Children.

Another 11-year-old boy is also at the hospital in a stable condition and is receiving treatment for leg and head injuries, and a 14-year-old girl is receiving treatment at Wishaw General Hospital for serious chest injuries.

A 13-year-old is in a stable condition at the Royal Hospital for Children and an 11-year-old boy at Wishaw General Hospital is in a similar condition. A 16-year-old boy is receiving treatment for an arm injury at the same hospital.

A 19-year-old man is being treated for a knee injury at Glasgow Royal Infirmary and a 19-year-old woman was treated for an injury to her wrist at Wishaw General Hospital and has since been released.

A 25-year-old woman who was passing the scene of the crash was also taken to Wishaw General Hospital for assessment and later discharged.

Detective Inspector John Malcolm said: "This is a really serious incident that has affected many people visiting the theme park and our thoughts go out to those who have been injured.

"We have now launched a joint investigation with the Health and Safety Executive and our priority is to find out the cause of the incident."

HSE principal inspector Barry Baker said: "Our thoughts are with the children and adults who have been injured in this incident and I must give praise to the emergency services and members of the public who came to their aid so quickly.

"We have brought HSE specialists in mechanical engineering to the site to begin the process of finding out what caused the gondolas to come off the rails. HSE will work very closely with colleagues in the police as the investigation unfolds."

It is not the first time M&D's has had problems with its rides.

In July 2011, nine passengers, including children, were stranded for more than eight hours when Tsunami came to a halt 60ft above the ground.

M&D's said the ride's lift chain broke and caused its safety systems to bring the carriages to a halt.

In March this year, eight people had to be rescued by firefighters in a cherry picker when the Tornado roller coaster at M&D's stopped working around 20ft off the ground.

According to M&D's, the Tsunami roller coaster can go at speeds of up to 40mph through corkscrew turns and loops.