Increased security measures are activated by the US and other countries at government, public buildings, and sports venues. On Monday April 15, 2013 two bombs exploded in the crowded streets at the Boston marathon in the United States.
The United States and other countries increase security in response to deadly bombings in Boston

1
New York Police Department officers investigate a commuter's bag in the Times Square subway station in New York during an increase in security following fatal explosions in Boston, April 15, 2013.

2
SWAT officers patrol the Copley Square area after explosions near the finish line of the Boston Marathon in Boston, Massachusetts April 15, 2013.

3
A sign is displayed by the road side warning of a British police security operation taking place along the forthcoming London Marathon route in London.

4
Tourists take pictures near a German police car guarding in front of the United States embassy in Berlin.