If you've just joined us: Two explosions near the finish line of the Boston Marathon - the oldest and most prestigious race of its kind in the US - have left at least three people dead and more than 100 injured.

The road was strewn with debris, and bloodied runners and spectators were treated at the scene; Boston's police commissioner urged city residents to stay indoors US President Barack Obama said it was not known what caused the blasts but vowed any group found to be responsible would feel the "full weight of justice"-- BBC