Boston bombs: FBI release images of 'armed and dangerous' suspects In front of the men as they walked was a woman in blue carrying what appeared to be several yellow balloons. A man the FBI labeled "Suspect 1" wore a dark baseball cap, a heavy dark coat over a white T-shirt, light trousers and boots, and was carrying a black backpack. "Suspect 2" wore a white baseball cap backwards on his head, a grey hooded top and dark coat, dark trousers and boot, and carried a white backpack. Both men had their backpacks slung over their right shoulders and walked a few feet apart, appearing not to communicate. But the FBI said it appeared they were "associated." Suspicions were first raised because "Suspect 2" was seen depositing his backpack at a spot outside the Forum restaurant where the second explosion happened. He dropped it minutes before the blast. After the bombings, Suspect 2 was seen heading west along Boylston Street. It was unclear where the other man went. Richard DesLauriers, the FBI's special agent in charge in Boston, said: "For more than 100 years the FBI has relied on the public to be its eyes and ears. These images will be delivered to millions around the world. We know the public will play a key part in finding them. Picture: FBI We consider them to be armed and extremely dangerous. No-one should approach them or try to apprehend them. Do not take any action on your own. If you see these men contact law enforcement. At this time these are the only people of interest to the FBI. He said agents had initially been looking at only one of the men as a possible suspect. The agent said: "Within the first day or so, we initially developed a single person of interest. Not knowing whether that person was working alone or in concert, we obviously worked with extreme purpose to make that determination. He said "all arms of the FBI worldwide" had worked to identify potential suspects. The FBI developed a second suspect. Today we are enlisting the public's help to identify the suspects," he added. Somebody out there knows these individuals as friends, neighbors, co-workers or family members of the suspects. Though it may be difficult, the nation is counting on those with information to come forward and provide it to us. No bit of information, no matter how small or inconsequential is too small for us to see. Each piece moves us forward towards justice. Mr DesLauriers added: "The images of Monday are indelible and the horror will remain with us forever." An FBI source told The Daily Telegraph that the pictures were likely to be sent to Scotland Yard, among other police forces around the world. However, that did not signify any suggestion that the suspects were linked to the UK. Asked about the images at a congressional hearing in Washington Homeland Security Secretary Janet Napolitano said: "There is some video that has raised the question of those that the FBI would like to speak with." She said the investigation is "proceeding apace." The blasts killed eight-year-old Martin Richard, 29-year-old Krystle Campbell and Lu Lingzi, 23, a graduate student from China. Seven victims remained in critical condition. The bombs were crudely fashioned from ordinary kitchen pressure cookers packed with explosives, nails and ball bearings. They exploded within 15 seconds of each other when thousands of runners were pouring in. President Barack Obama addressed Bostonians at an interfaith service at a cathedral about a mile from the bomb site, declaring "You will run again" and vowing to catch whoever was responsible.