There has been an explosion at Aldgate East underground station in London, causing the closure of the entire Tube network. There are also reports that a second incident took place at Edgware Road station in north west London. The Aldgate East blast was caused by "some kind of power surge", according to Tube infrastructure company Metronet, which is responsible for maintaining the Metropolitan line. A spokesman said: "We don't know the extent of the problem yet." A London Ambulance Service spokeswoman said: "We have just sent some resources out to the scene." British Transport Police confirmed that there are "walking...