It happened around 1:20 p.m. Thursday in the northbound lanes of Route 202 in East Goshen.
Police say two cars collided.
One of the vehicles went over the grassy median, across the southbound lanes and finally came to rest on the side of the road.
The other car ended up in the woods off Route 202.
One person was transported to Paoli Trauma Center, while the other victim is still on the scene.
Some lanes had started to re-open on the highway about an hour later.
