Three-star general may be among Pentagon dead

Deputy Defense Secretary Paul Wolfowitz: "We will mobilize our resources."

WASHINGTON (CNN) -- The number of people killed when a hijacked plane crashed into the Pentagon may have reached 190 and includes a three-star Army general, Pentagon sources said Thursday.

The figure takes into consideration the 64 people on the hijacked 757 that slammed into the southwest section of the sprawling defense office complex. The Defense Department is estimating that 126 Pentagon workers are still unaccounted for and believed dead in the aftermath of the terrorist attack.

As employees returned to work Thursday, bomb-sniffing dogs were sweeping through the Pentagon in response to an early-day bomb threat. The FBI received a telephoned threat during the morning rush as thousands of workers returned to the Pentagon, forcing a rapid evacuation. An all-clear message from investigators allowed everyone to return to the building a short while later.

As those 24,000 military and civilian employees reported back to work at the Arlington, Virginia, complex, damaged heavily from the impact of the airliner and a stubborn, subsequent fire, Metro subway trains resumed regular service to the facility's underground station and buses continued to operate from nearby Pentagon City.

Half of the building remains closed because of smoke and structural damage, and workers will have to double up in offices. Arlington County, Virginia, emergency officials said they are assuming they would find no more survivors.

As of Thursday, the Defense Department personnel believed to have been killed in the attack included 74 employees of the Army, 21 of whom were uniformed military, plus 47 civilian employees and six contractors working for the Army.

Thirty-three uniformed members of the Navy are believed to have died in the blast along with nine civilian employees of the Navy.

The Marine Corps and the Air Force believe they suffered no personnel losses.

Ten other people listed as "unaccounted for" are identified in a Pentagon statement only as employees of "defense agencies."

One informed defense official said that the toll could rise.

Human remains pulled from the Pentagon were being taken to Dover Air Force Base in Delaware to be identified, a fire official said.

Crews began removing victims' remains Wednesday afternoon but there was no word on how many bodies were recovered. By evening, crew members had started tearing down unstable parts of the building to continue their search. They hoped to have enough demolition work done by morning to enter the area.

"This has been a difficult couple of days," said Navy Secretary Gordon England at an afternoon Pentagon briefing. "We offer our prayers for all the families (of victims)… particularly for all Navy families."

"These 42 were serving the nation when they were attacked," added Admiral Vern Clark, chief of Naval operations. "Service… it is what our profession is about. These people committed their lives to being lives of consequence and lives of service."

Brig. Gen. Clyde Vaughn of the U.S. Army, director of military support, told reporters he was in his car on nearby Interstate 395 when the plane hit the Pentagon on Tuesday morning.

Vaughn said "I was scanning the air" as he was sitting in his car.

"There wasn't anything in the air, except for one airplane, and it looked like it was loitering over Georgetown, in a high, left-hand bank," he said. "That may have been the plane. I have never seen one on that (flight) pattern."

Georgetown is a sector of the District of Columbia jammed with shops and restaurants - it is one of the city's most vital tourist draws. Commercial aircraft that are either approaching or departing from nearby Ronald Reagan National Airport do not fly over Georgetown, and rather trace their flight route over the nearby Potomac River, which separates the district from South Arlington, Virginia, location of the Pentagon.

A few minutes later, Vaughn witnessed the craft's impact.

"You'll have several emotions… It's very complex," Vaughn said. "One is a tremendous amount of anger that we have countries that would support something like that. The next is tremendous emotional factor that deals with the people aboard that airplane. And the next is helplessness."

U.S. forces worldwide remain at ThreatCon Delta, the military's highest state of alert for terrorist attacks as security for American military personnel and their families was tightened.

The U.S. European Command's Web reported that Department of Defense Dependents Schools in Europe can return to normal operations beginning Friday.

For as much damage as was sustained by the building, for all the distraction and all the heartache, Deputy Defense Secretary Paul Wolfowitz hinted Thursday that a campaign of retaliation was in the works in the confines of the building.

Speaking of the costs already incurred since Tuesday, Wolfowitz said the $20 billion that was expected to be appropriated by Congress was a good start. But more might be needed.

"(That) is just a down-payment on what we're going to do," he said. "The people who have done this horrible deed against us and plan other deeds better realize that the American people are aroused … and we will mobilize our resources."

The campaign, Wolfowitz hinted further, would be drawn out.

"I think one thing is clear… You don't do it with a single military strike, no matter how dramatic. You don't do it with just military forces alone. You do it with the full resources of the U.S. government," he said.

"It will be a campaign, and not a single action. We're going to keep after these people and the people who support them until it stops."

-- CNN's Ian Christopher McCaleb contributed to this report.