If you were trying to travel through London Bridge station on Saturday afternoon, around 1:30pm then you may have run into a few delays.
The reason being that, according to the BBC, a power surge that sent "a flare 10 foot into the air from the track."
Eye witness reports from the Beeb describe a "fireball" moving along the track "like a Roman candle firework," with lots of smoke "and people were screaming and running out the station."
There was a small explosion like a firecracker. It went up quite high and started working its way down the track, it went about 120 foot and it lasted for about a minute.
There were lots of police sirens and then the station was evacuated and staff were comforting people.
The station was closed for about 30 minutes and there are no reports of anyone being hurt.