Rockets' Red Glare Lightens Stormy Day

Earlier, when the focus was on the threat of terrorism, the D.C. police had hundreds of officers augmenting U.S. Park Police patrols. Emergency workers looked for automobiles near the Mall rigged with explosives like those found in London last week.

The Park Police and the D.C. Emergency Management Agency had command centers monitoring activity along the route of the midday parade and at the Mall, but there were no arrests by early evening.

A long trailer near the U.S. Capitol was painted with the motto "Never Forget 9/11." Inside the vehicle, city and federal homeland security officials checked computer screens, police radio reports and video feeds to ensure that nothing marred the D.C. celebration.

"Everyone is up and monitoring," said Christopher T. Geldart, director of the National Capital Region for the Department of Homeland Security.

Inside the 38-foot-long operations center, emergency workers watched live video from downtown streets and peered at law enforcement alerts popping up on the computer: six anarchists at the World War II Memorial, 25 Code Pink activists at the National Archives, about 10 white supremacists sporting swastika armbands near the Washington Monument.

The District's Department of Transportation said it planned to test its emergency traffic signal-timing system after the fireworks, particularly along the Seventh Street-Georgia Avenue route to the Beltway.

A U.S. Park Police spokesman predicted a record crowd as the weather remained hot and moist in midafternoon and skies stayed clear. One official estimated that about 400,000 had come out for the celebration. As of 11 last night, Metro was reporting that more than 503,751 people had been on the rail system.

Authorities monitored the crowds from a police helicopter throughout the day. Officers were urged to look for vehicles with suspicious characteristics, such as protruding wires or an unusual odor.

"We actually have people staged at various locations along the parade route and the Mall," said Darrell L. Darnell, head of the D.C. Homeland Security and Emergency Management Agency. "A lot of the things we get are just people dehydrated."

On Alert for Threats

But officials were on the lookout for worse.

About midday, eight volunteer emergency workers in bright green vests set out from the mobile operations center to patrol the area. They carried a list of potential indicators of a car bomb: vehicles with sagging trunks, cargo covered by a blanket, the strong odor of gasoline.

"If you see something out of the way with a vehicle, give us a call," urged Kerry Payne, deputy operations chief at the Emergency Management Agency.