Federal officials may restrict truck traffic and fence sidewalks on 15th Street NW near the White House and Treasury Department, authorities said yesterday, as heavily armed police began inspecting cars, trucks and buses at more than a dozen checkpoints around the U.S. Capitol.

Secret Service and Department of Homeland Security officials confirmed that additional precautions next to the Treasury Department headquarters have been under discussion since Sunday, when the Bush administration announced a heightened terror threat to financial institutions in Washington, New York City and New Jersey. A decision could come as soon as today.

Scores of U.S. Capitol Police officers closed portions of First Street NE and set up roadblocks around Capitol Hill, scrutinizing car compartments, boarding Metro buses and asking some drivers to show identification. Across town at the International Monetary Fund and World Bank headquarters in Foggy Bottom -- the two specific Washington sites identified as terrorist targets in Sunday's announcement -- police activity was comparatively subdued. No-parking signs had been posted, a bomb-sniffing dog stood by and a few cars queued near Pennsylvania Avenue NW with trunks opened for inspection.

The checkpoints slowed traffic, particularly during the morning rush hour, but the blockades seemed to function smoothly, generating more weariness than complaints.

"From a security perspective and a traffic flow, I think it went very well," Capitol Police Chief Terrance W. Gainer said. "We were well-prepared, and traffic is light in August."

But the curtailed access to major roads around key symbolic and functional centers in Washington marked a dramatic acceleration of the creeping encroachment of security measures in the nation's capital in recent years. District leaders decried the steps yesterday, pronouncing them draconian and an overreaction whose legacy would be felt for years.

"We are fighting to preserve both security and freedom, not one or the other," Del. Eleanor Holmes Norton (D-D.C.) said at a noon news conference with Mayor Anthony A. Williams (D) on Capitol Hill. "We're not going to accept the closing of the city."

Even D.C. Police Chief Charles H. Ramsey complained about the actions, rare criticism leveled at his former chief deputy and close friend, Gainer. "I'm not pleased at all with it," Ramsey said. "We weren't part of any kind of planning. They just told us what they were going to do."

Williams and Norton said the restrictions would worsen already bad congestion, harm local businesses and could be avoided by using Jersey barriers to shunt traffic away from federal buildings.

Whatever approach is used, Norton said, federal authorities should not block the Capitol from the American people. "I don't care if it's a red alert," Norton said. "Their job is to think of ways to make us safe and keep us open at the same time."

Added Williams: "When in doubt, preserve freedom."

The Capitol street closure was approved by Senate Majority Leader Bill Frist (R-Tenn.), Minority Leader Thomas A. Daschle (D-S.D.) and the Republican chairman and ranking Democrat of the Senate panel that oversees rules for the Capitol, Sens. Trent Lott (R-Miss.) and Christopher J. Dodd (D-Conn.), according to Senate Sergeant-at-Arms William H. Pickle. House leaders went along but were less involved because the First Street closure runs between the Dirksen and Russell Senate office buildings.

Pickle said the decision was a "collective" one, based on intelligence briefings and a number of factors, including al Qaeda's habit of returning to earlier targets, the symbolism of the Capitol, the importance of "vehicle bombs as the weapon of choice" for terrorists and warnings of attacks in connection with the November elections.

There was no specific threat to the Capitol, he said.

Gainer also responded to critics: "By golly, it is inconvenient to people. It would have been inconvenient to people in August 2001 to increase security at the airport. But if we had done that, two airplanes wouldn't have flown into the World Trade Center and one into the Pentagon."

Restrictions on Capitol Hill soon could spread. Treasury, Homeland Security, Secret Service and District officials met last night, and a decision on possible new limits around the White House could come as early as today, two U.S. officials said.

Authorities may bar most trucks from a three- or four-block stretch of 15th Street NW just east of the White House and Treasury Department, between about E Street and New York Avenue, because of the threat from truck bombs, officials from two agencies said.

The Secret Service imposed a similar prohibition on an eight-block span of 17th Street NW on the west side of the White House in August 2002, enforced by electric road signs and uniformed Secret Service police officers.

In addition, Treasury officials are discussing closing the sidewalk on the west side of 15th Street alongside its headquarters, officials from two agencies said, to deter a suicide bombing.

Robert Nichols, a spokesman for Treasury Secretary John W. Snow, and Secret Service spokeswoman Lorie Lewis declined to comment about the proposal publicly. "A number of options are under consideration, but no final decision has been made," Homeland Security spokeswoman Valerie L. Smith said.

While D.C. Council member Carol Schwartz (R-At Large) protested that federal officials should "leave us alone," and Capitol Hill council member Sharon Ambrose (D-Ward 6) called the closures "a sneak attack on the District of Columbia based on old information," residents coped in the streets.

A number of Metrobus routes were delayed by the Capitol Hill closures and checkpoints -- Routes 30, 96, 97, A11, J11, N22, X3 and X8. Metro transit officials advised riders to visit www.metroopensdoors.com or call 202-637-7000 for details.

To Chris Adams, a coffee service delivery driver, having his truck stopped and searched by D.C. police in Foggy Bottom was just a part of doing business. "I'm fine with it,'' said Adams, 33, of Greenbelt. "If I can't make a delivery, my customers will know why.''

David Garrison, a Brookings Institution scholar, altered his walk to work to take in the checkpoints along Second Street NE but seemed unfazed by the sight of uniformed officers, concrete barriers and fluorescent orange traffic cones. "We're used to it up here on Capitol Hill," he said. "To some extent it seem like an overreaction, but how can we assess it as a private citizen?"

Practices varied from checkpoint to checkpoint. At the intersection of Second Street and Independence Avenue SE, 19 uniformed officers infrequently looked in vehicle trunks, while two blocks away at C Street, nearly every car was searched.

At Second Street NE, Robert Nettey was asked to pull over, produce identification and hand over his car keys. Officers did not explain why, he said.

An inscription on the Dirksen building affirms that "the Senate is the living symbol of our union of states." Yesterday the street beneath, nearly devoid of traffic, was unusually quiet.

Staff writers Dakarai I. Aarons, Arielle Levin Becker, Helen Dewar, Sari Horwitz, Lyndsey Layton, Daniele Seiss, Eric M. Weiss, Martin Weil and Del Quentin Wilber contributed to this report.

U.S. Capitol Police officers screen cars on First Street NE, part of an increase in vigilance after the terror threat level was raised.Del. Eleanor Holmes Norton (D-D.C.) and Mayor Anthony A. Williams hold a news conference to complain about the new D.C. street closures. U.S. Capitol Police guard checkpoints on First Street NE. More security measures may follow, officials say.