The A1(M) northbound is currently closed between junction 48 (Boroughbridge) and junction 49 (Dishforth) due to a serious collision.
Police were called to reports of a collision involving two HGVs at about 5am.
Emergency services are working at the scene. The road is expected to remain closed for some time.
Drivers are urged to avoid the area and use alternative routes, allowing extra time for their journeys.
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