An explosion has led to the closure of a major road.
North Yorkshire Police received a report at 3am this morning after an explosion was heard in the Catterick area.
There are no reports of any injuries, but the A1 motorway is closed at Catterick.
Both slip roads to Catterick have also been closed, diversions are in place and motorists are advised to avoid the area.
Police said this is a "precautionary measure" while they conduct inquiries.
On its Twitter feed, the force said Catterick village is "heavily congested" due to the A1 closure.
A spokeswoman for the Highways Agency said the closure takes in about a six-mile stretch of road.
The A1 runs adjacent to Marne Barracks, formerly RAF Catterick.
A spokeswoman for North Yorkshire Police said they do not know how close the explosion was to the barracks.
"At the moment it's only a heard explosion," she said, but she said it did come from that area.
There have not been any evacuations.
A spokesman for Catterick Garrison said the inquiry was police-led and did not have any information about how close the explosion was to the barracks.
On the Ministry of Defence website, Catterick Garrison is described as the army's "largest training establishment".
It covers 2,400 acres and 20,000 acres of training land.
The Garrison is situated just a few miles from the A1 and includes Marne Barracks near Catterick Village and the outstations of Ripon, Dishforth and Topcliffe.
A spokesman for the Highways Agency said the road is expected to remain closed until approximately 3pm.
Catterick Garrison provides a base for Headquarters 4th Infantry Brigade and Headquarters North East which forms part of 1st (United Kingdom) Division, according to the MoD website.
There are over 13,000 personnel, military, civilian and their dependants, living and working in the area.
Football fans are expected to be among the motorists affected by the road closure.
Newcastle United FC said they have notified West Ham officials that travelling supporters will be affected.
The northern football club are playing West Ham United today at the latter's Boleyn Ground in Upton Park, east London.