AN investigation is under way after 21 people were injured in a crash on a landmark Blackpool Pleasure Beach roller coaster.

One car had got stuck on the Big Dipper ride and was then shunted from behind by a following car, police said.

Three people were treated in hospital for facial, back and neck injuries, while 18 others were described by police as “walking wounded”.

They were all taken by ambulance to Blackpool Victoria Hospital for treatment following the accident, at around 7.50pm on Tuesday.

All 32 of the people on the ride at the time had to be rescued after the cars came to rest around 20ft off the ground, and firemen employed a specialist rope team and used stretchers and spinal boards to release the trapped victims.

The Big Dipper, a wooden roller coaster, first opened in 1923.

It is run by Blackpool Pleasure Beach, which has a number of bigger roller coasters on the same site on the resort’s South Shore.

A spokesman for Black-pool Pleasure Beach said: “Investigations are under way to establish the cause of an incident which occurred on the Big Dipper wooden roller coaster on Tuesday at approximately 7.50pm.

”Emergency services attended the incident. There were 32 riders in total.

"The Big Dipper will remain closed while investigations continue but all other rides at Pleasure Beach will open as usual at 10.30am.

”The Pleasure Beach team are working closely with the emergency services and the Health and Safety Executive to establish the cause of the incident.”

Of the 21 people admitted to hospital, the youngest was seven and the oldest 51.

One man, aged 25, had facial injuries, likely to require surgery, and another person is believed to have suffered a minor arm fracture, but the majorityhad neck and back pain with minor bruises to legs, arms and chest.