An air ambulance has landed on the front lawn of Alton Towers theme park after a guest became unwell on a ride.
Thrill-seekers are reportedly being told to stay away from the grass area while the person is being treated.
Fire brigade units have also been spotted at the park.
An Alton Towers spokesperson confirmed a visitor to the park became 'unwell' on the ride Thirteen.
They said: "The air ambulance was called to provide medical assistance to a guest who had fallen ill during their visit.
"This is common practice when support is requested. We would like to reassure our guests that this was unrelated to any of our rides or attractions."
Thrill-seekers took to social media in shock as the chopper lowered into the park.
One said: "Air ambulance and fire services at #altontowers and thirteen has been shut off completely. Hope everything is OK and everyone is safe."
Another wrote: "An Air ambulance has landed on the Towers front lawn, hope nothing bad has happened."
The condition of the person who fell ill is currently unknown.
Thirteen, which opened in 2010, was the world's first vertical free fall drop rollercoaster.
Guests on the ride plunge five metres in pitch black darkness.
The coaster, which replaced the Corkscrew, cost £15,000,000 to build.
