Maybe we're on a Speed (1994) situation.

There's a bomb in the bus. It will activate once we go past a certain speed. Once it activates, we can't go below a certain speed.

Also, the bus driver is injured, and a random lady with no driver's license or bomb-defusing experience is now driving. Furthermore, a part of the track is missing. Also, all passengers are hysterical.

That's more like what's happening right now.