Devon and Somerset police received a call at 4.39pm alerting them to the incidents on the eastbound A361 carriageway from Tiverton towards the M5, around 3 miles from Tiverton.
Both accidents, reported to have been between the A361 Bolham Road junction and the A396 Heathcoat Way junction, are thought to have occurred because of the weather.
No one has been injured.
Inspector Graham Thomas of Devon and Cornwall Police said: “It looks like potentially they were linked to the weather.
“It may be that a vehicle has aquaplaned, although we are not sure of the circumstances yet.
“One of the vehicles has gone through the central reservation.”
One lane is closed. The fire service has attended to ensure the vehicles involved are safe.