Northumbria Police is leading the emergency service response to the incident on the A69 near Haltwhistle.
The road has been closed in both directions to allow officers to conduct collision investigations.
National Highways is sending resources to assist with traffic management and the road is expected to remain closed in both directions throughout the morning.
Diversions are in place.
Eastbound traffic should follow the solid square diversion symbol on local road signs, turning left on to theB630 at Greenhead Bank, then right on to the B6318 to Chollerford.
Turn right at the Chollerford roundabout then right again on to the A6079 towards Hexham. Continue through the villages of Wall and Acomb, then urn left to rejoin the A69 eastbound carriageway
Westbound traffic should follow the solid triangle diversion symbol on local signs. Turn right at the Acomb junction on to A6079. Continue through the villages of Acomb and Wall, then turn right on to the B6318 at Low Brunton crossroads. Take the first exit at Chollerford roundabout, staying on the B6318, turn left on to the B630 in Greenhead, then right to rejoin the A69 westbound at Greenhead Bank.
Drivers are being urged to allow extra journey time or even reroute or delay their journey.
Further information is available from National Highways by visiting www.trafficengland.com website and travel apps, or via the regional twitter feed. The agency’s contact centre team is also available to provide up to the minute information on 0300 123 5000.