Five police officers have been taken to hospital after their landrover overturned on the main Derry to Belfast road.
The collision occurred on Glenshane Road close to the Baranailt Road junction near Claudy at around 7.30am this morning.
No other vehicle was involved.
Motorists are being advised to seek alternative routes or expect long delays.
Translink says its 212 Goldliner Derry to Belfast service is experiencing delays of between 20-30 minutes.
The five officers were taken to Altnagelvin Hospital for treatment to injuries which are not thought to be life-threatening.
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