London Fire Brigade (LFB) is at Charing Cross railway station dealing with a fire. The LFB Twitter account says the front carriage of a Southeastern train caught fire, clearly seen in this video posted to Instagram by vincenzo_minore. The fire is at the end of the platform nearest the concourse (Charing Cross is a terminus).
Various witnesses on social media report a train hitting the end of a platform unable to stop; however the LFB says it was a "small fire... about 5% of the carriage was alight" despite dramatic images. The fire is under control, the station has been evacuated and there are no injuries. You should expect significant disruption to your journey if you're travelling on routes connected to Charing Cross today (and we'd recommend checking before you travel tomorrow morning).