Officials say a separatist group is responsible for a knife attack Saturday that killed 29 and injured 130.
Anyone caught sneaking past the starting line or onto the path mid-race will be in trouble.
Russia has 40,000 police and military staff on the ground for the Olympics. Will it be enough?
City buses and trains are vulnerable to terrorists, but trying to make them safer would ruin them.
A few months after the marathon bombing, Ed Davis talks about civil liberties with more nuance than Ray Kelly.
If this discussion sounds familiar, it's because we've had it before.
Street artists decry the "hypocrisy" of the President's plea for military action in Syria.
Smallpox maliciously released in London would spread to several countries before governments could intervene, a new model predicts.
There was more gas than usual on the New York City subway system Tuesday morning, if that's even possible.
Religious groups can be capable -- and sometimes incredibly deft -- at policing extremists within their own ranks.
People around Boston didn't stay inside Friday because the city forced them to. And this distinction matters.
Much of last night's action took place in Cambridge and Watertown, a western suburb of Boston.
All transit has been suspended; residents urged to remain in their homes. Police are conducting a door-to-door manhunt for second bombing suspect.
Makeshift memorials from around the city.
There are millions of men and women wandering around America who spent the best years of their lives in this city.
The bombings have turned all the cues and surroundings of this time of year upside down.
The city of Boston is blanketed with security cameras. But finding the right shots is a little like looking for a needle in a hay stack.
Early reports suggest at least one of the bombs used in yesterday's Boston Marathon attack was hidden in a garbage can. There's a case to be made for removing them all.
New York, Los Angeles, and Washington, D.C. have stepped up police presence on transit, at tourist attractions, and near hotels.