U.S. raises terror alert for transit systems No reports of threats to U.S. Gli stati uniti rialzano l'allarme terrorismo per i sistemi di trasporto. Nessuna segnalazione di minaccie sugli USA (segue in ENG)

Thursday, July 7, 2005;

United States raises threat level for transit systems(3:40)
Witness describes bombing at underground station(2:48)
U.S. train security put to the test(3:15)

The Bureau of Consular Affairs has set up a call center for inquiries on U.S. citizens in London who may have been affected by the blasts. The call center number is 1-888-407-4747. So far, the bureau has no information about any American citizens injured or killed in the attack.

(CNN) -- U.S. mass transit systems were put on higher alert after Thursday's bombings in London, with officials in major cities urging Americans to go about their business but be on the lookout for anything suspicious.

Homeland Security Secretary Michael Chertoff raised the alert level to orange, or high.

He said the order was not a result of any "credible information suggesting an imminent attack here in the United States," but was taken out of concern about possible "copycat" attacks.

Chertoff said the heightened alert covers regional and inner-city passenger rail, subways and metropolitan bus systems.

Officials said the Department of Homeland Security planned to release an advisory bulletin to federal, state and local government officials and law enforcement late Thursday in which it will outline its concerns about continued terrorist interest in mass transit systems.

The bulletin will not mention specific intelligence, a senior Homeland Security official said.

Officials stressed that they do not have any specific or credible threats against transit systems in the United States, but said Thursday's events in London and "some other generic threat streams that have strategic-level importance" have focused efforts on preventing rail attacks.

The national passenger rail network Amtrak increased its security level by inspecting tracks and deploying more officers and canine teams at stations. Transit systems coast to coast took similar steps. (Full story)

In New York, where the 2001 al Qaeda attacks on the World Trade Center killed nearly 2,800 people, city and state officials urged straphangers to be more aware of their surroundings and report any suspicious packages immediately.

"We know what it's like to be attacked," Gov. George Pataki told reporters. "But we know what it's like to live in freedom and in confidence, and that's what we have got to do."

New York Police Commissioner Ray Kelly told CNN his officers were "doing everything that's prudent, everything that we reasonably can do to protect the city."

But he said it was impossible to put a police officer "on every train all the time, or one on every station all the time."

"New Yorkers are tough people. They realize that there are certain risks they have to assume," Kelly said. "I think they also realize that the government is doing everything that we reasonably can do to protect them."

In Chicago, police tightened security around the central business district and transit system, and Mayor Richard M. Daley said his office was staying in touch with federal Homeland Security officials.

"They are not suggesting that people change their travel plans, but they have called for increased vigilance from passengers and authorities," Daley said.

Similar steps were being taken on subways, buses, airports and train stations in major cities nationwide.

Many of those steps were launched immediately after the bombings hit three trains and a double-decker bus during London's morning rush hour, killing 37 people and wounding 700.

British Prime Minister Tony Blair blamed Islamic extremists for the bombings and vowed to bring those responsible to justice.

In Washington, the Metro transit police sent special teams armed with machine guns and accompanied by bomb-sniffing dogs to patrol subway stations, trains and buses.

Capitol Hill police Thursday announced plans to search buses, tour vans and larger vehicles traveling on the roads leading to the Capitol. Security also was tightened around the Pentagon.

Congress is out of session for the Independence Day break. The House and Senate are scheduled to convene again next week.

Secretary of State Condoleezza Rice and Defense Secretary Donald Rumsfeld signed a condolence book at the British Embassy in Washington.

The U.S. Army band played "God Save the Queen" outside the embassy Thursday evening, and the State Department lowered the Union Jack to half-staff outside its Washington headquarters.

"I want to express our sympathy and our prayers for the families of those who have died and our prayers and wishes for the recovery of the injured," Rice said. "I also want to say that we have no better friend, and ally, in the struggle against terrorism than Great Britain."

People left dozens of flower bouquets and signs with messages such as "We stand with you" and "Today, we are all British" against the front gate of the embassy.

President Bush was attending the Group of Eight economic summit in Scotland when the bombing occurred.

"We will not yield to these people, will not yield to the terrorists," he said. "We will find them, we will bring them to justice, and at the same time we will spread an ideology of hope and compassion that will overwhelm their ideology of hate."