[JURIST] Prime Minister Tony Blair gave a statement Thursday [transcript] at 10 Downing Street after a series of four incidents saying "We have to react calmly and continue with our business. We know why these things are done – they are done to scare people and make them feel worried." Sir Ian Blair [official profile], London Metropolitan Police Commissioner, said earlier Thursday, "We know that we have four explosions, four attempts at explosions, and it's still pretty unclear as to what's happened." The events took place at three underground areas and on a double-decker bus; Warren Street, Oval, and Shepherds Bush, and on a bus headed from Waterloo to Hackney.

For more official information as the situation develops:

UK goverment emergency page
London Metropolitan Police news page
London Transport news
10 Downing Street
UK Home Office
UK Resilience
Mayor of London
London Prepared
London Strategic Emergency Plan
Royal London Hospital

11:40 AM ET – AP is reporting only one injury and no fatalities in the explosions Thursday that bear many similarities to the July 7 bombings two weeks earlier [JURIST report]. AP has more.

1:52 PM ET – Reuters is reporting that there may be some unexploded devices on London's transport system. Metropolitan Police Commissioner Ian Blair has said that "there is obviously forensic material at these scenes which may be very helpful to us." Reuters has more.