(CNN)Here is a look at the Boston Marathon terror attack. On April 15, 2013, double bombings near the finish line of the Boston Marathon killed three people and injured at least 264.
The bombs exploded 12 seconds apart near the marathon's finish line on Boylston Street.
Martin Richard, 8, a student at Neighborhood House Charter School in Boston.
April 15, 2013 - At approximately 2:50 p.m., two bombs explode near the finish line of the Boston Marathon. The bombs explode within 8-12 seconds of each other, about 50-100 yards apart.