Boston explosions: Student heard 'loud booming sounds'
15 April 2013 Last updated at 22:34 BST
Two people have been killed and 23 injured after two explosions at the finish line of the Boston Marathon, police say.
The blasts shattered the carnival atmosphere of one of the biggest sporting events in the US, causing panic and confusion.
Bloodied victims were initially rushed to a medical tent set up to care for fatigued runners.
Taylor Dobbs a journalism student in Boston told the BBC "there were two very loud booming sounds and I ran out on to my back porch to see if there was anything going on".