Three children injured when a roller coaster derailed at a theme park in North Lanarkshire are still in a serious condition in hospital.

A total of ten people were hurt when the carriage came off the rails on the Tsunami coaster at M&D's in North on Sunday afternoon.

They were taken to nearby hospitals including the Royal Hospital for Children in Glasgow, where four children are being treated.

Three are in a serious condition, while the fourth is stable. Liam Boyle, 11, is among the crash victims and was on the roller coaster when it derailed.

The schoolboy was badly injured in the crash and it was feared he may lose his arm or hand but his grandfather confirmed doctor's had saved Liam from permanent damage after surgery.

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."

One adult is also in a stable condition at Glasgow Royal Infirmary and four children and adults are being treated at Wishaw General Hospital. Another child has already left hospital.

Five gondolas appear to have come off the rails as they were rounding a bend and fell under 20ft, police said. Witnesses said people were left trapped upside down following the incident at around 3.40pm.

Katie Mcardle was at the theme park with boyfriend William Murray when the roller coaster went off the rails at 40mph. The student was trapped upside down after the carriage she was in plunged onto a children's ride.

She wrote on Facebook: "I have never been so scared in my entire life. Honestly thought I was going to die, sitting in that carriage upside down with everyone screaming. Turning round and not seeing William beside me was the worst. We are honestly so so lucky, there is definitely someone watching over us both.

"We are both still in shock and have a few injuries but just so lucky to be alive. "Not seen William since it all happened but I here he's doing alright." Katie said she had been "badly hurt" with bruises and a broken wrist and that her boyfriend was still being treated for a dislocated knee.

She added: "We are both badly hurt with bruises. I have a broken wrist and bruised and battered and William's knee came out of place and he's also bruised badly."

James Millerick, who helped injured children at the scene, told STV News: "A carriage from the Tsunami ride had fallen off completely and scraped through a metal gate.

He added: "People were trapped underneath because it had fallen upside down. It went straight through the metal gate, crushing it."

M&D's has been closed while an investigation is carried out by Police Scotland and the Health and Safety Executive.

Police Scotland chief inspector David Bruce said: "Along with other emergency services we attended immediately and on arrival it became clear that a series of five gondolas connected on a train on the Tsunami ride have detached from the rails, struck the superstructure and then struck the ground."

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.

A spokeswoman for the theme park added: "A serious incident occurred at M&D's involving the Tsunami roller coaster.

"We have all emergency services on site to assist. The theme park is closed until further notice."