An earlier version of this graphic said the suspects robbed a 7-Eleven in Cambridge. State police are backing off that assertion.

    On Thursday at 5 p.m., the FBI released video and photos of two suspects wearing hats and carrying backpacks toward the
    Boston Marathon finish line minutes before two bombs exploded, killing three and injuring 176.

    2:38 p.m.

    Video shows suspects moving through crowd

    Suspects 1 and 2 are seen turning from Gloucester Street onto Boylston Street and walking toward the marathon finish line. Suspect 1, Tamerlan Tsarnaev, is in front and wearing a dark hat. Suspect 2, his younger brother Dzhokhar Tsarnaev is following, wearing a white cap turned backwards.


    2:41 p.m.

    The brothers stand together about one-half block west from the Forum restaurant.


    2:42 p.m.

    Tamerlan Tsarnaev walks east on Boylston Street, toward the finish line. He passes directly in front of the Forum and continues in the direction where the first explosion will occur in seven minutes. His knapsack is still on his back.

    2:45 p.m.

    Dzhokhar Tsarnaev walks east on Boylston. He stops directly in front of the Forum and stands near the barrier separating spectators from the runners. He puts his knapsack onto the ground. A photo taken from across the street shows the knapsack at his feet.


    Dzhokhar stays in front of the Forum for about four minutes, occasionally looking at his phone and appearing to take a picture with it. Approximately 30 seconds before the first explosion, he lifts the phone to his ear as if he is speaking, and keeps it there for 18 seconds. A few seconds after he finishes the call, the first explosion goes off. The crowd around him can be seen turning their heads east, toward the explosion. Dzhokhar glances to the east, and then calmly but rapidly walks west, away from the finish line. Approximately 10 seconds later, the second explosion occurs in the same location where Dzhokhar left his knapsack.

    Investigators used footage from surveillance cameras along Boylston Street to help identify the suspects.

    Photo taken after the explosion on Monday. (Credit: EPA)

    Investigators zero in on video footage

    Officials initially said a camera at Lord & Taylor was of “special interest,” but they later determined that those on the North side of the street, where the explosions happened, were more helpful.

    Authorities report over a hundred injured and three deaths
    after two explosions near the Boston Marathon finish line.


    Explosion near finish line

    The first explosion occurred about 2:49 p.m. near the intersection of Boylston and Exeter streets.

    Credit: WHDH


    Another blast

    The second explosion occurred seconds later, about 50-100 yards down the road. Smoke from the first explosion can be seen in the background of this photograph.

    Credit: WBZ-TV/AP


    Unrelated incident at library

    Initial reports of another explosion at the John F. Kennedy Library in Boston turned out to be an unrelated fire.