Motorists heading west on the A38 through Plymouth are being told to follow diversions put in place by National Highways after a crash.
Just before 6pm tonight, traffic website Inrix reported that the A38 is closed westbound with queueing traffic because of an accident between the B3416 at Deep Lane junction and the A374 Plymouth Road at Marsh Mills roundabout.
Rush hour traffic is dealing with the congestion that has built up on the A38 and on alternative routes through Plympton and Plymstock.
National Highways posted on its website: "Traffic on the eastbound carriageway is currently stopped for Air Ambulance to work at scene.
"Emergency services including Devon and Cornwall Police are in attendance. National Highways Traffic Officers are also on scene assisting with traffic management."
The agency added: "If this closure impacts on your planned route, please allow extra journey time. Plan ahead, you may wish to re-route or even delay your journey.
"Further information is available from National Highways by visiting our www.trafficengland.com website and travel apps, or via our regional X ( Twitter ) feed. Our 24/7 contact centre team is also available to provide up to the minute information on 0300 123 5000."
A38 Diversions Set Up After Crash Near Plymouth