Eight children and two adults have been taken to hospital after a rollercoaster derailed at a theme park in Scotland.
Eyewitnesses said the Tsunami ride at M&D's amusement park in Motherwell, near Glasgow, had been full when it came off the track shortly before 3.50pm.
Police, firefighters and paramedics rushed to the scene as several visitors posted images on social media appearing to show a mangled carriage on a pathway surrounded by dozens of people.
Police Scotland originally said 11 people had been hurt, but later revised it to 10. A force spokesman said there were nine passengers on the ride at the time.
Speaking to reporters at the scene, 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.
"We have launched an investigation and an inquiry between Police Scotland and the Health and Safety Executive (HSE)."
Mr Bruce added: "They (the gondolas) fell less than 20 feet. It would appear that they have been coming round a bend and at that point it has detached. At this stage it's very, very early in the inquiry and we are still taking witness statements, but the gondola had been in operation on the rollercoaster and it would appear that it has been coming round a bend.
"It's an inverted rollercoaster which means that the riders hang in gondolas below the rails rather than sit above them.
"It would appear to come off as it has come round a corner. It struck the ground, but it hadn't struck anything on the ground.
"I don't know what speed it would have been travelling but it was operating and rollercoasters do travel at speed."
People reacted with shock both at the scene and on social media.
First Minister of Scotland Nicola Sturgeon wrote on Twitter:
Ruth Davidson, leader of the Scottish Conservative Party, said: "Awful news coming from M&Ds. Deeply concerning - our thoughts are with those affected and with emergency responders."
Richard Lyle MSP, whose constituency includes Strathclyde Country Park, where the theme park is situated, called for a "full investigation" into the incident.
He told STV: "I'm totally concerned and horrified at this terrible accident."
In one image, taken by Dean Borris, people can be seen trapped upside down in their seats on the carriage, with their legs protruding into the air.
Katie Burns said she had just finished riding the Tsunami rollercoaster and was walking past when the carriage crashed with children on board.
On Facebook, she said: "Literally got off the Tsunami at M&Ds and then walking past and the next lot of people get on and the full thing goes off the tracks. Honestly never been so scared in my life, with this weather they should not be on.
"Kids and adults are still on it upside down, it's like something out a horror film, children crying and everything.
"Literally can't believe this, my heart goes out to everyone on it, a full load came off the track and on the pavement, like a horror film worse thing ever heard and seen, can't get over this."
She posted an image of one of the rollercoaster wheels on the pavement.
A video posted on social media showed the confused aftermath of the crash, with staff warning the crowds to give emergency services room to work.
A man in a purple uniform can be heard saying: "The best thing you can do is back away and give them some space."
Another staff member then puts a cordon in place around the wreckage of the carriage as bystanders look on in horror.
Witness James Millerick, who was queuing for another rollercoaster at the theme park, said he heard "shrieks" from customers.
He said there was talk that someone had come off one of the rides and rushed over.
"When we got there the rollercoaster had come off the track entirely - straight through the gated fence at the side of the rollercoaster and was upside down on the concrete path at the side," he told Sky News.
"There were maybe seven or eight individuals, mostly of younger age between maybe 10 and 15 years old that were actually trapped inside the rollercoaster lying on the ground. The harnesses were still on as well so there was absolutely no movement."
He said he thought the rollercoaster had slipped off the tracks as it came around a corner but did not fall from the highest point.
A spokesman for the Scottish Ambulance Service said six ambulance crews, a specialist operation team and emergency doctors were on the scene.
According to the M&D's website, the Tsunami rollercoaster can go at speeds of up to 40 miles per hour through corkscrew turns and loops. Children under 10 are not allowed to use the ride, and under 14s must be accompanied by a paying adult.
It is not the first time the park has had problems with its rides, including Tsunami.
In July 2011, nine passengers, including children, were stranded for more than eight hours when it came to a halt 60 feet above the ground.
A spokesman at the time said the ride's lift chain broke causing its safety systems to bring the carriages to a halt.
And in March this year, eight people had to be rescued by firefighters in a cherry picker after the Tornado rollercoaster stopped working around 20ft off the ground.