Two bombs at Boston Marathon cause at least two deaths and many serious injuries; more devices present

Two bombs killed at least two and injured dozens other at the finish line of the famous and heavily-attended Boston Marathon in Boston, Massachusetts, on the east coast of the USA.

At approximately 2:45p local time, about 4 hours and 9 minutes after the start of the race according to the clock at the finish line, there were two explosions, blowing out storefront windows, severing limbs and causing the deaths of at least two people. Two more unexploded devices were found and dismantled or exploded by police. Race winners had finished about two hours earlier, but there were still many racers running and crossing the finishing line. Runners not yet in the area were diverted according to an emergency plan, and the rest of the race was cancelled. The time of the detonation was within minutes of peak finishing time of 2012's marathon.

A third explosion also occurred at Boston's JFK Library and Museum and was being treated as related. 

About half a million people line the raceway to see the race of some 20,000 people, and many go to the finish line to watch their friends and family finish, making the area where the bombs exploded very densely populated.

Authorities indicate that at least one of the bombs seems to have been homemade. No claim has yet been made for the bombing.