(NBC News) Investigators believe the bombs at the Boston Marathon were shrapnel-studded pressure cookers, hidden in backpacks and set off by timers, law enforcement officials told NBC News on Tuesday.
According to the NBC News report:
The disclosure came as authorities pleaded with spectators from the race to send photos and video that may shed light on who set off the blasts, killing three people and injuring at least 176.
The top FBI official in Boston vowed to go “to the ends of the earth” to find those responsible. But a day after the explosions, President Barack Obama said authorities still did not know whether the attack was foreign or domestic, the work of a group or an individual, or what the motive might be.
Law enforcement officials told NBC News that the explosives were classified as low — meaning that they traveled at under 3,300 feet per second. That is not enough to create a blast wave, which can kill people from air compression and blow out faraway windows, but it is enough to propel the shrapnel a great distance.
Read the entire NBC News report HERE.