Two cows were killed after a herd escaped from a field in Devon and wandered on to a road.
Thirty cows escaped near the A380 close to the Ideford dip at about 0400 GMT.
Two were then hit by a car and the rest scattered across both carriageways. Police closed the road for an hour to try to catch the rest of the animals.
They said a number were still in the area and could wander on to roads. Motorists have been warned to drive with care.