Head of the metropolitan Police, Sir Ian Blair, said in the wake of the London bombing that it will be very difficult now to determine the death toll, but it will be at least 50.
Yet, he said there are around 700 wounded, with 22 serious or critical.Ã‚Â Besides, there were bodies in the Tube train at Russle Square however, the figure will unlikely to top 100.
Four blasts occurred in one hour, hit three Tubes and one double Decker bus which, according to eyewitnesses, was packed with passengers who turned out of the Tubes.
Police sources said a massive intelligence investigation is under way to find those responsible.
The Police chief said so far we can not rule out that the bombings were suicide attacks.
Intelligence started recovering CCTV material in bid to identify the attackers.
Anti-terrorist branch chief, Andy Hayman said the explosive devices weighed around 4.5 Kg (around 8 pounds) of high explosives that could be carried in a rucksack.
Some media sources speculated that at least one of the attacks was carried out by a suicide bomber.
One passenger who left the bus moments before the blast was quoted by some London newspapers as saying that he saw a nervous man in his mid-20s fiddling with his bag.
‘This chap started dipping down into his bag and getting back up. He did it about a dozen times in two or three minutes and looked extremely agitated,Ã¢â‚¬Â said Richard Jones, 61, an IT consultant.