Details have emerged about the bombs used in the attack the killed three people and and injured more than 170 at the Boston Marathon yesteray.
What was in the bombs? How were they developed and manufactured? Who has used this type of bomb before? Here's what you need to know.
1. The Bombs Were Made From Pressure Cookers
According to recent reports, the devices were made from pressure cookers. A similar bomb-making strategy was used in one of the devices used in the 2010 Times Square bombing in New York City.
2. They Resemble IEDs Used in Afghanistan
IEDs, or Improvised Explosive Devices, is essentially a homemade bomb. AP reports pressure-cooker bombs "have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 joint FBI and Homeland Security intelligence report." Such devices can be triggered remotely with a cell phone. Boston shut down cell phone service in the wake of the attack.
3. The Devices Were Reportedly Transported in Backpacks or Duffle Bags
According to NBC News, the devices were transported in backpacks:
JUST IN: #BostonMarathon devices were placed inside backpacks and appear to have been transported to scene in those packs
— NBC News (@NBCNews) April 16, 2013
In addition, at a 5 p.m. EST press conference, the FBI asked the public if anyone had any information about someone with black nylon bag.
4. They Were Reportedly Put in Trash Cans
Then, after they were transported to the finish line at the Boston Marathon, they were dumped into or near trash cans. Reportedly, the bombs were designed to look like pieces of trash so people wouldn't notice them. Other reports say they were left on the ground.
5. They Were Filled with Ball Bearings
The devices were apparently filled with ball bearings, based on the material removed from victims. In addition, they contained shards of metal and nails as well. At a 5 p.m. EST press conference, officials confirmed this, and said they found "pieces of black nylon, which could be from a backpack”... [which were] sent to Quantico, Va., for analysis."