Scariest Public Transport Experiences

What are some scary experiences you've had on public transport? One time a person on the train who was clearly on drugs was waving a knife around and talking to himself about beating people up. It hadn't left the station yet and the police came and escorted him out of the station.

This one isn't scary but would have been if it had happened a bit later - a few years ago I was about to get on one of the Eurotunnel shuttles and as we were driving down the ramp the locomotive caught fire, with smoke coming through the cab door. We were held up and were eventually put on another train, but if the loco has caught fire when we were on the move that could have been disastrous.