波士顿爆炸案后美国全境提高安保级别

波士顿马拉松爆炸案发生之后，美国国内从世贸中心、时报广场，到白宫及各类体育场馆均提高了安保级别，警方增派了重点场所的巡逻警力，并派出反恐小分队参与安保工作。执法部门通过社交网站呼吁公众向警方报告任何可疑行为和活动。纽约市出动了危急情况反应小组和1000多名反恐工作人员，对帝国大厦、洛克菲勒中心和联合国总部等人群密集的场所进行重点监控。其他各州也都增加了警方巡逻密度，同时加强了对桥梁、隧道及铁路线路的安全监控。与此同时，大洋另一边的英国也在加紧为周三的撒切尔夫人葬礼布置安保方案，届时女王伊丽莎白二世和各界名人均会出席。受波士顿爆炸案影响，英国警方正在重新审查将于本周日举行的伦敦马拉松的安保方案。

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 former Prime Minister Margaret Thatcher. The event at St. Paul's Cathedral, to be attended by Queen Elizabeth II and other dignitaries, calls for a procession through the streets of London, with Thatcher's flag-draped coffin carried on a horse-drawn carriage.

British police were also reviewing security plans for Sunday's London Marathon — the next major international race — because of the bombs that killed three people and injured more than 140 in Boston.

Across the U.S., 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 being especially monitored.

Mayor Michael Bloomberg said the police department was fully prepared to protect the city.

"Some of the security steps we are taking may be noticeable," Bloomberg said. "And others will not be."

In Washington, Secretary of Homeland Security Janet Napolitano urged the American public "to be vigilant and to listen to directions from state and local officials."

"At the president's direction, the Department of Homeland Security is providing any support necessary in this ongoing investigation," Napolitano said.

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 and other onlookers were still allowed in the park across the street.

Speaking late Wednesday from the White House, President Barack Obama declared that those responsible would "feel the full weight of justice," though he urged a nervous nation not to jump to conclusions and pointedly avoided using the words "terror" or "terrorism."

However, top lawmakers declared the deadly incident an act of terrorism, and a White House official said it was being treated that way.

Police in Los Angeles, Washington, San Diego, Las Vegas, Detroit, Atlanta and other major cities were monitoring events closely and assessing increases in security measures.

In California, emergency management officials activated their statewide threat assessment system, which was established after the Sept. 11 attacks. And officials in multiple cities and counties throughout the state were reviewing information from federal authorities for possible threats.

In Seattle, police increased patrols in neighborhoods and around government buildings and other facilities. In Colorado a statewide alert was sent out advising law enforcement agencies to look out for suspicious activities.

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.

And at the Port of Los Angeles and Long Beach, as well as at three major Los Angeles airports, including Los Angeles International, law enforcement officials were in a "heightened state of vigilance," with increased patrols, authorities said.