Tube warning after 'bang' heard - bomb?

"More here.

Emergency services have been called to London's Liverpool Street Underground station after reports of an explosion. The incident has caused major disruption to the entire network with stations across the capital closed.

A London Fire Brigade spokeswoman said four crews were at the scene and more were on their way. There are reports of "walking wounded". Cordons are in place. A power failure may be behind the problems, Transport for London said.
Probly nothing but there was no power on parts of the tube this morning which correlates with some kind of incident."
RantBurg

I found this from this morning, RantBurg reports what at the time looks like power outage or a malfunction in the tube. Read the comments as the morning progresses and the reality sets in.