NEW YORK (AP) — Major transit agencies beefed up security as a precaution today following the suicide bombing in Moscow's subway system.

New York's Metropolitan Transportation Authority had a "heightened security presence," said spokesman Kevin Ortiz. He declined further comment. The agency is in charge of New York City buses and subways, as well as suburban trains, and bridges and tunnels.

In Washington, D.C., Metro police were conducting random inspections of stations and rail yards. Metro Transit Police's acting head, Jeri Lee, said today that the agency was doing "what we can to be as secure as possible."

Russian authorities said two women blew themselves up in Moscow today in a subway jam-packed with rush-hour passengers, killing dozens. They blamed the carnage on rebels from the Caucasus region.

Representatives of transit agencies in Boston and Philadelphia said they believed their normal security practices were vigilant enough to protect the riding public.

The federal government did not immediately make any recommendations for increased security at mass transit systems, but authorities were monitoring the situation, a U.S. official said. The official spoke on condition of anonymity to discuss internal deliberations.