One person is in a critical condition following a fairground ride accident at Cavendish Park in Barrow.
Cumbria Constabulary said that two other others were also injured and also transferred to hospital.
The incident occurred at about 20:30 on Saturday, but details of its nature or the ride involved are not yet clear.
Furness Coastguard described it as a “major incident” after it was called at about 21:30 to attend via helicopter.
Police, ambulance, fire and air ambulance services all attended the scene at the Fudstock music festival.
The injured were taken to Furness General Hospital, where one female and one male were later released.
On Sunday afternoon, police said that the critically-injured female had been transferred to Royal Preston Hospital.
The unspecified ride was at Cavendish Park as part of the Fudstock festival, which was reportedly ended early and cleared of visitors following the accident.
In a statement released on Sunday morning, event organisers said there had been a “serious incident” on one of the fairground rides present.
“Our thoughts and best wishes are with those involved, as we await further news,” the statement read.
“We appreciate this is upsetting and we’d ask people to be kind and not speculate out of respect to the families and friends.”
The Health and Safety Executive (HSE) was notified of the incident, and has now opened a joint investigation with Cumbria Police.