UPDATE (10:45 p.m.): President Barack Obama stopped short of calling Monday’s bombing in Boston an act of terror, but security officials around the world are treating it that way.
From New York City to London, officials deployed additional security teams in major metropolitan areas. Boston officials don’t yet know who planted the bombs near the finish line of the Boston Marathon, but no one is taking the chance that the attack was an isolated incident.
The next international marathon will take place in London on Sunday. Security officials there already are on high alert as they prepare for former Prime Minister Margaret Thatcher’s ceremonial funeral on Wednesday. Queen Elizabeth II and other dignitaries plan to attend the event at St. Paul’s Cathedral. The service will be preceded by a procession through the streets of London.
In the United States, officials tightened security at landmarks, government buildings, transit hubs, and sporting events.
In New York, critical response teams moved in packs with lights on and sirens blaring across the city. More than 1,000 counterterrorism officers patrolled monuments and buildings that attract large crowds, including the United Nations complex and the World Trade Center.
During his brief address Monday evening, President Obama said whoever planted the bombs would not escape unpunished: "We will find out who did this. We'll find out why they did this. Any responsible individuals, any responsible groups, will feel the full weight of justice."
UPDATE (9:00 p.m.): Boston police commissioner confirmed that three people have been killed in the explosions near the finish line of the Boston Marathon. The explosions Monday also injured more than 130 people, knocking spectators and at least one runner off their feet
EARLIER REPORT: Some of the victims lost arms and legs. Other injuries included broken bones, shrapnel wounds and ruptured eardrums.
Two bombs exploded near the finish of the Boston Marathon on Monday, leaving two people dead and injuring 23 others, according to police.
One runner, a state trooper from Rhode Island, said he saw at least two dozen people with very serious injuries, including missing limbs.
"I started running toward the blast. And there were people all over the floor," he said. "We started grabbing tourniquets and started tying legs. A lot of people amputated. … At least 25 to 30 people have at least one leg missing, or an ankle missing, or two legs missing."
A third blast shook the John F. Kennedy Library several miles away and more than an hour later, but no injuries were reported, police said.
Organizers are currently working with authorities to determine what happened, but the explosions may have come from a nearby building, according to Cherie Falgoust, a spectator who was waiting for her husband at the finish line.
"I was expecting my husband any minute," she said. "I don't know what this building is … it just blew. Just a big bomb, a loud boom, and then glass everywhere. Something hit my head. I don't know what it was. I just ducked."
Around 27,000 runners took part in the 26.2-mile race, one of the world's most popular marathons.
The bombs went off about two hours after the winners crossed the finish line.
Runners who had not finished the race were diverted onto another street and into a family meeting area, according to an emergency plan already in place.
The Associated Press contributed to this report.