Investigators have found a circuit board believed to have been used to trigger the Marathon bombs, a source told the Globe's Shelley Murphy.
A TSA supervisor at Logan Airport has told his security people to ask travelers who looked like they had attended the Marathon if they took any photos near the finish line that they would be willing to turn over to officials investigating the bombings.
Although MGH has enough blood for now, it has a shelf life, and these patients will need transfusions over the coming days and weeks. Doctors do not want to have to throw out blood because they got too many donations now, but then run short later when they need it.
None of MGH's patients will be discharged today.
Most of the amputations done at MGH were above the knee because there was so much damage to the patients' legs.
According to Globe colleague Nick Cafardo, the Yankees will play Sweet Caroline tonight out of respect for Boston Marathon victims.
There were a few patients who arrived at MGH in very, very critical condition; doctors are convinced that if they had remained at the scene for even a few more minutes, they would not be alive today. They credited emergency services and medical personnel at the scene with getting patients to the city's many hospitals rapidly.
MGH doctor says they had very little discussion with the patients when they arrived because most were in a state of shock. "At the point we were rushing to save their lives; they were bleeding profusely. That wasn't the time for talking; it was the time for doing."
MGH doctors say that most patients they saw have extensive burns as well as extensive injuries from the shrapnel from the bombs.The hospital sent some patients with ruptured eardrums from the blast next door to Mass. Eye and Ear.
One of the bombs was placed inside a metal pressure cooker hidden inside a backpack, according to Channel 7. Some were constructed with a low-velocity explosive.
Emerson student Daniel Chamberlain, a sophomore film major, made this video after the Boston Marathon explosions.
A patient at Tufts-New England Medical Center holding a press conference now was near the finish line watching a female friend who was running. He said the explosion was like a cannon going off. He thought maybe it was bad fireworks: "it never dawned on me there would be a device or bomb there. It shattered the window next to us and I realized something was going on. I looked over at my wife and I saw that her lower leg was hit by shrapnel and she was bleeding."
The Tufts patient led his wife into a nearby store and using clothes from a rack, wrapped a tourniquet around her leg. They then went back outside to see if they could help others. His wife eventualy was put in an ambulance and taken to the hospital.
Medford Mayor Michael McGlynn spoke to the father of 29-year-old Krystle Campbell, said "she was the daughter everyone wanted." Although Krystle recently moved to Arlington, her parents live in Medford.