Protesters march on Pakistan PM Nawaz's house
Two explosions near the finish line of the Boston Marathon killed three people and injured more than 150 on April 15, 2013. Security tightened in cities across the country as the investigation began.
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The NYPD shows a strong and increased presence in Times Square in New York City on April 15, 2013. Many American cities are on alert after two bombs exploded near the crowded finish line of the Boston Marathon killing two people and injuring more than 125 others. UPI/John Angelillo
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