Two explosions hit the Boston Marathon as runners crossed the finish line, killing at least two people and injuring many others. Photo: Reuters

Two bombs exploded in a crowded street near the finish line of the Boston Marathon in Massachusetts, the US, on Monday, killing at least three people and injuring more than 140. Local media expect the number of reported causalities to rise. The first bomb exploded at 3pm local time near the finish line. A few seconds later, a second bomb went off about 100 meters down the street. Mobile phone service in Boston was temporarily suspended to prevent remote detonations. Boston police said a third bomb targeted the John F.Kennedy library about 8 kilometers away. No damage from the third bomb has yet been reported. US President Barack Obama has announced that the US is implementing all necessary security measures. No group or individual has claimed responsibility for the bombings.