US Homeland Security raises transit terror alert

The United States Department of Homeland Security has raised the terror alert level to "orange" for trains in reaction to the bombings of three subway trains and a bus in London.

The United States has a five-level terror alert system in which orange is the second-highest level.

Homeland Security Secretary Michael Chertoff asked citizens for increased vigilance and asked cities to increase their security on their transit systems.

"Currently, the United States has no specific, credible information suggesting an imminent attack in the United States," says Chertoff.

The United States Coast Guard, part of the Department of Homeland Security, has alerted stations in high-risk areas to stand 24/7 patrols.

In Washington, Capitol Hill police announced plans to search buses, tour vans and larger vehicles traveling on the roads leading to the Capitol.

In San Francisco today, local police stood guard at Muni and BART stations. Amtrak rail lines released a statement saying that they are stepping up their security around their country-wide stations. Local sheriff dispatches have been seen patrolling even the smallest rail stations.