-- Eight of the 31 patients at Massachusetts General Hospital were in critical condition late Monday, trauma surgeon Peter Fagenholz said. The most serious wounds "have been combined, complex lower injuries that involve blood vessels, bone and tissue," and several underwent amputations, he said.
-- The bombings resulted in at least 10 amputations and left doctors picking ball bearings out of victims in the emergency room, a terrorism expert briefed on the investigation said.
-- In addition to the patients treated at Massachusetts General, 33 patients were treated at Beth Israel Deaconess Medical Center; 23 at Boston Medical Center; 18 at Tufts Medical Center; 31 at Brigham and Women's Hospital and 13 at Brigham and Women's Faulkner Hospital;10 at Boston Children's Hospital; five at Carney Hospital; 18 at St. Elizabeth's Medical Center; and one at Newton-Wellesley Hospital.
-- Officials in other cities, including London, Washington, New York, Miami, Chicago and Los Angeles, said they were monitoring events and had stepped up security.
-- London Met Police Chief Superintendent Julia Pendry said: "A security plan is in place for the London Marathon. We will be reviewing our security arrangements in partnership with London Marathon." That marathon is scheduled for Sunday.
-- "This was a heinous and cowardly act and, given what we now know about what took place, the FBI is investigating it as an act of terrorism," Obama said Tuesday at the White House after meeting with key advisers about the Boston Marathon bombing.
-- The flags at the White House, like those on Capitol Hill on Monday, were lowered Tuesday to half-staff.
-- In a telegram to Cardinal Sean O'Malley, archbishop of Boston, a spokesman for Pope Francis said, "At this time of mourning, the Holy Father prays that all Bostonians will be united in a resolve not to be overcome by evil, but to combat evil with good (cf. Rom 12:21), working together to build an ever more just, free and secure society for generations yet to come."
-- A number of professional sports teams held moments of silence Monday night.
-- The Virgin London Marathon will mark 30 seconds of silence before this Sunday's race and is urging runners to wear a black ribbon to mark the Boston events.
-- Saudi Ambassador to the United States Adel bin Ahmed Al-Jubeir condemned the bombings. "What occurred ... in Boston is a heinous crime which contradicts the values of humanity," he said.