The closure in both directions is between the A169 and the B1248 near Malton and at the moment there is no indication of when it will re-open.
A spokesperson for National Highways said: "Police lead the response to the ongoing incident and have closed the carriageway to allow them to work at scene. Due to the nature of this incident we are not able to advise how long the closure is likely to remain in place."
They added that police are diverting traffic locally and asked people to allow extra time for journeys if this closure impacts their route.
Police are diverting traffic locally.