Officers from Lancashire Constabulary were called to a farm in the Moor Lane area about 4.25pm on Tuesday following a report of a serious accident.
It was reported a Polaris Ranger pulling a trailer had fallen into a river after a bridge collapsed. Eleven people were in the vehicle and trailer at the time of the incident, police said.
The Settle-based Cave Rescue Organisation was called in by police to help with the rescue operation.
Despite the presence of emergency services including police, ambulance crews, fire crews and mountain rescue, one man suffered fatal injuries and was pronounced dead at the scene.
A second man suffered a serious head injury and was taken to Royal Preston Hospital for treatment.
A third person suffered a serious back injury and was taken to Royal Lancaster Infirmary along with a number of others who were injured in the incident.
Police said an investigation into the circumstances around the incident is underway and the Health and Safety Executive has been informed.
A statement from the Cave Rescue Organisation said: "The team were called to attend an incident in Roeburndale alongside police, ambulance and fire crews.
A sad outcome and our thoughts are with the family and friends of the deceased, and with others involved, or affected, by this tragic incident."
"Detective inspector Kirsty Wyatt, of Lancashire Constabulary, said: “My thoughts are very much with all those involved in what is a very sad and tragic incident.
“One man has sadly died and a number of people have suffered serious injuries.
“At this time we believe the vehicle was pulling the trailer, containing a number of people, when a bridge gave way. Those people were then thrown from the vehicle and trailer.
“Our investigation is at very early stages and enquiries are ongoing to establish what happened.”
Anyone with information which can help police is urged to call 101 quoting log 0953 of January 18.