From the World Trade Center and Times Square in New York to the White House and sports venues across the country, police patrolled in packs and deployed counterterrorism teams Monday as security was stepped up after explosions at the Boston Marathon.
Worries also reverberated across the Atlantic, where an already robust security operation was being beefed up for Wednesday’s ceremonial funeral for Margaret Thatcher, the former prime minister. The event at St. Paul’s Cathedral, to be attended by Queen Elizabeth II and other dignitaries, calls for a procession through London’s streets, with Thatcher’s flag-draped coffin carried on a horse-drawn carriage.
British police were also reviewing security for Sunday’s London Marathon — the next major international race — because of the bombs that killed at least three people and injured more than 130 in Boston.
There is no known specific or credible threat against the British race at the moment, a security official said.
The London Marathon is a hugely popular race. Last year, some 37,500 athletes competed, with many more watching the springtime event. Seven members of Parliament are scheduled to take part.
The Boston explosions were front-page news in Britain and elsewhere around the world, with The Sun website blaring “Marathon Slaughter, Three Dead in Bomb Carnage” and The Evening Standard proclaiming “Blasts Horror at Boston Marathon.”
The explosions in Boston sparked alarm in Britain, where a massive security operation was put in place last summer to protect the successful London Olympics.
The UK used military units to police the games, including antiair missiles based on some apartment buildings. In the two weeks before the Olympics, police arrested 14 people in two counterterrorism probes as part of a 66-day operation to prevent a terrorist attack during the Olympics.
Across the United States, security was tightened at landmarks, government buildings, transit hubs, and sporting events. Law enforcement agencies also urged the public via Twitter and Facebook to report suspicious activity to the police.
In New York, authorities deployed so-called critical response teams — highly visible patrol units that move in packs with lights and sirens — along with more than 1,000 counterterrorism officers.
Highly trafficked areas like the Empire State building, Rockefeller Center, St. Patrick’s Cathedral, the United Nations, and the World Trade Center site were especially monitored.
At the White House, the Secret Service expanded its security perimeter after the attacks, shutting down Pennsylvania Avenue and cordoning off the area with yellow police tape. Several Secret Service patrol cars blocked off entry points, although the White House was not on lockdown and tourists were allowed in the park across the street.
In California, emergency management officials activated their statewide threat assessment system, established after the Sept. 11 attacks.
In New Jersey, authorities raised security statewide, calling in off-duty state police officers and deploying bomb units, aviation crews, tactical teams, and search and rescue assets as a precaution.
Transit and port officials in New York and New Jersey were on heightened alert at bridges, tunnels, and on rail lines between the two states, as well as on New York City’s subway system and commuter rails.