The Boston Marathon says that small homemade bombs caused the two explosions heard at the finish line and that organizers were working with authorities to determine what happened.
Organizers made the announcement on the group’s Facebook page on Monday.
Authorities have headed onto the course to carry away the injured while stragglers in the 26.2-mile race were rerouted away from the site.
The Associated Press reports two deaths and dozens were injured and a number suffered serious injuries including loss of limbs. They also report that two other devices were found at the marathon, and were being dismantled.