London police are searching for four "would-be" bombers after three subway trains and a bus were targeted with explosives that failed to detonate Thursday.
Investigators searched Friday for fingerprints, DNA and other forensic evidence collected from attacks on three subway trains and a double-decker bus that were hauntingly reminiscent of suicide bombings only two weeks before, reports the AP.
Two men were detained - one near the scene of one attack and another near Prime Minister Tony Blair's Downing Street residence - but both were later released without charge, police said.
Four suspected terrorists fled the sites of bombings with passengers, leaving behind vital evidence, police said.
"This may represent a significant break-through in the sense that there is obviously forensic material at these scenes which may be very helpful to us," Metropolitan Police Commissioner Sir Ian Blair said at a press conference yesterday. Ha added, he felt "very positive about some of these developments," says Bloomberg.
Three of the explosive devices used on Thursday were the same size and weight as those used on July 7, the British Broadcasting Corp. reported. Three of the bombs were also again carried in rucksacks. While the explosives failed, the detonators probably went off, causing small blasts, the BBC said.