Police and the Health and Safety Executive have begun an investigation into a "serious accident" at a quarry.
Unconfirmed reports suggested the incident at Harden Quarry, in Biddlestone near Rothbury, Northumberland, involved a vehicle falling some distance.
Five ambulance crews were sent to the remote scene following a call at around 10.38am.
A North East Ambulance Service spokeswoman said one of the crews was from the Hazardous Area Response Team.
Three fire engines and a specialist rescue unit were also scrambled.
The Great North Air Ambulance Service was alerted but the call was stood down before the helicopter flew to the scene.
A Northumbria Police spokeswoman said: "The Health and Safety Executive and police are investigating a serious accident at Harden Quarry at Biddlestone, Northumberland, today."