Firefighters were called to a road traffic collision on the A48 near Woolaston on Sunday evening.
One fire engine from Lydney fire station, help with a crew of five, and one from Cinderford fire station, with a crew of six, were immediately mobilised to the incident.
On arrival, it was found that two injured adult males had already been released and were being treated by colleagues form South West Ambulance Service.
One adult female was still trapped in her vehicle and the crews commenced her extrication immediately.
Once the lady was released from the car, all three casualties were conveyed to hospital by the ambulance crews.