A young runner, left, stops by a Boston church blocks away from the scene of the bombings. The blasts exploded near the Boston Marathon's finish line on Monday, April 15, killing three people and injuring more than 170 others. <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2FSPECIALS%2Fus%2Fboston-bombings-galleries%2Findex.html">See all photography related to the Boston bombings.</a>
Boston: The aftermath of terror —
A young runner, left, stops by a Boston church blocks away from the scene of the bombings. The blasts exploded near the Boston Marathon's finish line on Monday, April 15, killing three people and injuring more than 170 others. See all photography related to the Boston bombings.
Spencer Platt/Getty Images
Unclaimed finish line bags litter the ground near the bombing sites. A day after the terror attack, authorities warned city residents to keep their guard up amid a massive investigation into the bombings.
Boston: The aftermath of terror —
Unclaimed finish line bags litter the ground near the bombing sites. A day after the terror attack, authorities warned city residents to keep their guard up amid a massive investigation into the bombings.
Spencer Platt/Getty Images
Investigators work at an area of the crime scene on Boylston Street on April 16.
Boston: The aftermath of terror —
Investigators work at an area of the crime scene on Boylston Street on April 16.
Darren McCollester/Getty Images
Blood is visible on a sidewalk in front of a Boston store on April 16.
Boston: The aftermath of terror —
Blood is visible on a sidewalk in front of a Boston store on April 16.
JESSICA RINALDI/reuters/LANDOV
Flowers rest against a police barricade down the street from the Boston Marathon's finish line on April 16.
Boston: The aftermath of terror —
Flowers rest against a police barricade down the street from the Boston Marathon's finish line on April 16.
JUSTIN LANE/EPA/LANDOV
Unused thermal blankets for runners are piled high near the scene of the bombings on April 16.
Boston: The aftermath of terror —
Unused thermal blankets for runners are piled high near the scene of the bombings on April 16.
Spencer Platt/Getty Images
National Guardsmen look out from inside Boston's Back Bay Station on April 16.
Boston: The aftermath of terror —
National Guardsmen look out from inside Boston's Back Bay Station on April 16.
Darren McCollester/Getty Images
U.S. military Humvees move down deserted Boylston Street on April 16.
Boston: The aftermath of terror —
U.S. military Humvees move down deserted Boylston Street on April 16.
JOHN MOTTERN/AFP/Getty Images
National Guardsmen patrol the Back Bay Station on April 16 as security remains tight in Boston.
Boston: The aftermath of terror —
National Guardsmen patrol the Back Bay Station on April 16 as security remains tight in Boston.
Darren McCollester/Getty Images
Pedestrians pass National Guard troops at a roadblock on April 16.<br />
Boston: The aftermath of terror —
Pedestrians pass National Guard troops at a roadblock on April 16.
Spencer Platt/Getty Images
The unfinished meals of fleeing customers are left on tables at an outdoor restaurant in Boston on April 16.
Boston: The aftermath of terror —
The unfinished meals of fleeing customers are left on tables at an outdoor restaurant in Boston on April 16.
Spencer Platt/Getty Images
People congregate at a security gate near the blast scene on April 16.
Boston: The aftermath of terror —
People congregate at a security gate near the blast scene on April 16.
Spencer Platt/Getty Images
A man jogs down a street near the scene of the bombings on April 16.
Boston: The aftermath of terror —
A man jogs down a street near the scene of the bombings on April 16.
Spencer Platt/Getty Images
A woman sits alone at a Boston cafe on April 16.
Boston: The aftermath of terror —
A woman sits alone at a Boston cafe on April 16.
Spencer Platt/Getty Images
A woman carries a sign she made to support her runner husband near the scene of the bombings.
Boston: The aftermath of terror —
A woman carries a sign she made to support her runner husband near the scene of the bombings.
Spencer Platt/Getty Images
A police officer stands on duty in Boston on April 16.
Boston: The aftermath of terror —
A police officer stands on duty in Boston on April 16.
Spencer Platt/Getty Images
People have breakfast at a Boston cafe on April 16.
Boston: The aftermath of terror —
People have breakfast at a Boston cafe on April 16.
Spencer Platt/Getty Images
A Boston police officer stands near blast sites April 16.
Boston: The aftermath of terror —
A Boston police officer stands near blast sites April 16.
Spencer Platt/Getty Images
National Guard troops man a roadblock April 16.
Boston: The aftermath of terror —
National Guard troops man a roadblock April 16.
Spencer Platt/Getty Images
A Boston police officer is heavily armed blocks away from the scene of the bombings.
Boston: The aftermath of terror —
A Boston police officer is heavily armed blocks away from the scene of the bombings.
Spencer Platt/Getty Images
A runners bib lies discarded April 16. <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2FSPECIALS%2Fus%2Fboston-bombings-galleries%2Findex.html">See all photography related to the Boston bombings.</a>v
Boston: The aftermath of terror —
A runners bib lies discarded April 16. See all photography related to the Boston bombings.v
Spencer Platt/Getty Images