BILOXI, Miss. (AP) — A freight train crashed into a bus full of Texas tourists visiting Gulf Coast casinos, killing four in Biloxi, Mississippi.

Forty people were hurt, seven critically. The cause of the Tuesday afternoon crash is under investigation.

Witnesses told Mississippi news outlets the bus appeared to have been stuck on the tracks when it was hit. The crossing is on a steep embankment and has a sign warning drivers that it has a low ground clearance.

Authorities on the scene said it took more than an hour to get everyone aboard the bus out of the wreckage. Two people had to be removed with metal-cutting equipment. The CSX Transportation locomotive pushed the bus about 300 feet before coming to a stop with the mangled bus still straddling the tracks.