Map: How the Boston Marathon bombings happened

First explosion

The first blast comes at 2.50pm as runners finish the marathon, on the pavement behind crowds to the left of the athletes’ route just a few hundred feet before of the finish line.

Second explosion

Just 13 seconds after the first blast, a second explosion occurs less than 100m away, on the same side of the road, further back along the route.

Controlled explosion

A third explosive device is found after the finish line, and is destroyed by authorities.

John F Kennedy Public Library

An incident, possibly a fire, is reported at the nearby John F Kennedy Library. It is still unclear whether this is related to the bombings, or whether it was an unrelated fire. An investigation is ongoing.