Three teenagers have been found dead after a black Audi A3 came off the road at Panns Bank near Wearmouth Bridge in Sunderland and entered the River Wear just before 13:30 BST.
Northumbria Police confirmed that four people were in the car. A 17-year-old boy managed to reach safety and is currently in hospital with non-serious injuries. He has since been arrested in connection with the incident.
The bodies of two teenage boys and a teenage girl were recovered from the water. No other vehicles are believed to have been involved in what Ch Supt Scott Cowie described as "a truly tragic incident."
Tyne and Wear Fire and Rescue Service, the North East Ambulance Service, and RNLI teams were involved in the rescue efforts. The investigation is at an early stage as police work to establish the circumstances.