Government agencies sent in medical supplies, dogs to sniff for victims and portable morgues.

The government began implementing an emergency response plan, in the works for decades, immediately after two airplane attacks on New York's World Trade Center. Minutes later, a third plane crashed into the Pentagon.

Bush, who started his day at a Sarasota, Fla., elementary school, was flown to military bases in Louisiana and Nebraska before returning to the White House Tuesday evening.

The Secret Service took immediate steps to ensure that the president, Vice President Dick Cheney and House Speaker Dennis Hastert were safe, said Karen Hughes, a top Bush aide. Agents also took precautions for members of the national security team, the Cabinet and senior White House staff.

Top congressional leaders were sent to a secure government facility 75 miles west of Washington. They returned Tuesday evening. The House and Senate each planned to convene at 10 a.m. Wednesday for the sole purpose of passing resolutions condemning the attacks. They will recess until Thursday morning, when normal business resumes.

Across the globe, American forces and embassies went on high alert.

Transportation Secretary Norman Y. Mineta and other senior White House staffers gathered at a White House command center, where they coordinated with other branches of federal government. Secretary of State Colin Powell was returning to Washington from South America.

The Federal Emergency Management Agency activated eight urban search-and-rescue task forces for New York and four for the Pentagon. The 62-member teams provide emergency medical care, help stabilize damaged buildings and include dogs trained to search for victims.

FEMA's emergency response has been plan in place since the early 1990s, spokesman Marc Wolfson said.

``We have had exercises, we have had training, we have had meetings with the agencies involved,'' he said. ``Now it's a matter of getting through this situation. We will be here to help.''

The Health and Human Services Department sent four teams of volunteer doctors, nurses and other medical staff to New York. Three teams of about 35 specially trained, private, volunteer medical professionals were on their way to Washington.

In an unprecedented move, HHS Secretary Tommy Thompson activated a national medical emergency system that will send roughly 7,000 volunteer doctors, nurses, pharmacists and other medical staff to areas affected by Tuesday's attacks.

He said all of the agency's 80 disaster teams, spread around the country, are ready to go where needed. It was the first time all the teams have gone on alert.

HHS was also sending teams of morticians, anthropologists and forensic scientists to New York and the Pentagon to help identify the dead and prepare them for burial. It was also sending emergency supplies, including portable morgues.

The Federal Aviation Administration grounded all flights until at least noon EDT Wednesday, the first time the nation's entire air traffic system had been shut down. Many international flights in the air were diverted to Canada.

The Federal Reserve operated throughout the day and officials there reported no disruptions to the nation's banking system.

The President's Working Group on Financial Markets, composed of officials from the Fed, the Treasury Department, the Securities and Exchange Commission and the Commodity Futures Trading Commission, conferred throughout the day on developments in financial markets around the world.

Treasury spokesman Robert Nichols said that while Treasury Secretary Paul O'Neill was in Tokyo, the last stop of an Asian tour, other top Treasury officials monitored developments at a ``secure location.''

Nichols said that the U.S. Customs Service, responsible for border operations, went to the highest alert level, meaning that inspectors were asking travelers more questions and conducting more extensive examinations. Customs last went to a Level One alert in December 1999 after federal authorities stopped a car loaded with explosives entering the country from Canada.

At the Justice Department, officials set up a hot line for families who feared their relatives may have been victims of one of these attacks.

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Associated Press writers Genero C. Armas, Anjetta McQueen, Lauran Neergaard, Martin Crutsinger and Jeannine Aversa contributed to this report.