The incident happened at around 2.15am today (Sunday, February 17) on Wakefield Road in Liversedge.
West Yorkshire Police Road Traffic officer Dave Cant tweeted these dramatic pictures from the scene this morning.
He said: "Wakefield Road Liversedge - Closed. Anticipated it will be closed for a while."
Arriva tweeted to say that the 254 and 268A services are diverting via Union Road in both directions.
We're waiting for confirmation on the injuries sustained in the accident, and will update this story once we know.