David Bloom, the NBC correspondent who captivated the country by narrating the war in Iraq from a refurbished tank he helped design, died there yesterday of a pulmonary embolism.

Bloom, 39, who dropped his co-anchoring duties on "Weekend Today" to head to the war zone, was on the air around the clock. Millions saw him reporting from what colleagues dubbed the "Bloommobile" in sandstorms, in a headset, in night-vision goggles, his dirt-streaked face sometimes illuminated just by a pair of glow sticks.

"Early on he said, 'I want a piece of this war,' " NBC News President Neal Shapiro said yesterday. Shapiro recalled "this incredible energy he had. What his last series of reports showed was that he was able to relate to people in a very human way, talking to the guys in the tanks. That reached through the lens."

Bloom was drawn almost magnetically to breaking news. When the Washington sniper story broke last fall, NBC anchor Tom Brokaw called Washington bureau chief Tim Russert and said: "Bloom is chomping at the bit." The former White House correspondent was dispatched from New York to lead the network's coverage.

"He was unstoppable," Russert said. "You would have to chain him to the desk."

Bloom is the second American journalist to die in the Iraq war. Atlantic Monthly editor-at-large and Washington Post columnist Michael Kelly was killed in a Humvee accident Thursday night while with soldiers trying to escape enemy fire. While Bloom's death was not combat-related, the stress and long hours he spent in the tank could have contributed to the fatal blood clot that began in his leg.

NBC executives said Bloom was in excellent health. But in an interview from Iraq a week ago, Bloom, who was embedded with the Army's 3rd Infantry Division, spoke of having to sleep in his tank recovery vehicle with his knees propped up against him.

A pulmonary embolism occurs when a blood clot formed elsewhere in the body is carried to the chambers on the right side of the heart. From there the clot is pumped into the lungs where it usually breaks up, preventing blood from picking up oxygen. Prolonged immobility increases the chance that a blood clot can form in the leg. While patients immobilized after surgery have higher rates of leg clots and pulmonary embolism, some research suggests that prolonged travel in cramped spaces may also increase the risk.

Despite the difficult conditions, Bloom spoke in the interview with rapid-fire enthusiasm about the long hours, the journalistic challenges and the nerve-racking experience of coming under Iraqi fire. But he was equally excited in describing how a group of mechanics was trying to repair a Bradley fighting vehicle engine in a dense sandstorm. "We're here to tell the soldiers' stories," he said.

"This was going to be his war," said CNN's Walter Rodgers, who trained with Bloom at a Pentagon boot camp. "He was going to make his mark. He knew he was going to elbow the rest of us out of the way."

With his boyish good looks and bubbly personality, the 10-year NBC veteran, who usually began phone calls with "Hey, buddy," always seemed ticketed for stardom. But those who might have been inclined to view him as a self-promoting pretty boy were won over by his sheer doggedness.

"He was so clearly a star presence that you might have gotten sick of him, but you couldn't help but love David," said ABC's Claire Shipman, who shared a cubicle with him when both covered the White House for NBC.

"He was incredibly charming and really worked it in a big way," a crestfallen Katie Couric told viewers yesterday.

Former White House spokesman Joe Lockhart said Bloom was initially viewed as a handsome "lightweight," but "there was a slow but perceptible change as people realized this guy was a hard worker and a straight shooter. He'd call me several times a day and say, 'Tell me something no one else knows. You've gotta help me out here.' " At briefings, said Lockhart, "he'd ask the same question of me 12 times in a row."

Friends say Bloom talked constantly about his wife, Melanie, and their three young daughters. In the interview, Bloom said he could relate to a soldier who couldn't be home for a child's birthday because he felt bad about having just missed the birthday of his 9-year-old twins.

Bloom brought passion to every endeavor, and Russert recalled taking the amateur hockey player to a Washington Capitals playoff game. "My side was sore from his elbows," Russert said. They also had serious discussions about faith and religion after Bloom converted to Catholicism.

A high school debate champion in his native Minnesota, Bloom started in television in 1989 at WTVJ, the NBC station in Miami, where he quickly became known for his bulldog tenacity. During Hurricane Andrew, he walked up to a looter making off with boxes of merchandise.

"You're trying to hide your face," Bloom declared as the cameras rolled. "Are you embarrassed as you're doing this?"

Bloom jumped to the network in 1993, reporting from Chicago and then Los Angeles on stories as diverse as the U.S. military buildup off Haiti, the siege of the Branch Davidians in Waco, Tex., and the O.J. Simpson murder trial. He was on Bob Dole's plane during the 1996 presidential campaign and soon moved to the Clinton White House.

"Working with David was like drinking 10 cups of coffee," Shipman said. "You did not want to compete against David because he was tireless. During the Monica Lewinsky story, I'd listen to him wheedle and cajole tidbits out of the lawyers who could not tell him no. He would not take no for an answer."

Bloom would rock back and forth in his chair as he typed, Shipman recalled, reading his script aloud: "Tom, the White House tonight denied . . . "

At a NATO meeting in Madrid, Bloom charged up to a roped-off area to ask President Clinton about a White House scandal development. "Stay on me, I'm going in," he told his cameraman. Bloom laughed it off when Clinton got even by skipping him at the next news conference.

Yesterday, Clinton called Bloom "a smart, energetic professional whose enthusiasm for the job was evident in every question he asked and every story he covered."

During a presidential trip to China, colleagues said yesterday, Bloom went to a police station to try to interview a newly arrested dissident, then tracked down the man's family and stayed up all night finishing the piece. The next day he was high-fiving his crew.

Bloom joined "Weekend Today" in New York three years ago, and co-anchor Soledad O'Brien recalled him joking his way out of an awkward moment when the teleprompter broke during his first appearance. "He was a warm and funny, funny person," she said. "He was so loved on the show."

When Bloom was asked to do what O'Brien called "completely ridiculous things" -- riding a mechanical bull or reporting on winter wear for dogs -- he would proclaim with mock indignation: "This is killing my credibility. I was a White House correspondent!" But even when Bloom dressed up in a leisure suit and wig for a '70s disco show, she said, "he really got into it."

In the fall of 2001, when Brokaw received an anthrax-laced letter, Shapiro asked Bloom to hold off on looking into the planned visit of federal investigators to the 30 Rockefeller Center headquarters, feeling it was no time for a reporter to be nosing around.

"He called me back 20 minutes later and said, 'Here's who's in the building and here's who they're meeting with,' " Shapiro said. "He was one of the most competitive and aggressive journalists I've ever met."

During the run-up to the war with Iraq, Bloom worked with technicians in creating a mobile satellite transmission unit that could be mounted on an M88 tank recovery vehicle and transmit sharp pictures at up to 50 mph. The camera sent microwave signals to a converted Ford crew-cab truck several miles back in the convoy, where the images were beamed to NBC.

"He conceived of how to do it and what parts he needed," Russert said. "He'd call up and say, 'We need one last part, but we need a license from the State Department.' No one thought he could do it."

Network executives were thrilled with Bloom's emerging role as the unofficial travel guide to the war, and his dispatches, which also played constantly on MSNBC and CNBC, drew praise from affiliate stations. "The stuff from David Bloom in the tanks is so effective," said an e-mail from WAGT in Augusta, Ga. "The pieces filed by David Bloom this morning are incredible," said WSTM of Syracuse, N.Y.

From Iraq, Bloom sent O'Brien e-mails about how he was craving pizza and hoped to be home soon, urging her not to worry. He called his old boss at Miami's WTVJ, and people were lined up down the hall to talk to him.

On Saturday night, colleagues said yesterday, Bloom called the MSNBC news desk in Secaucus, N.J., to check on the scores of the Final Four basketball games, then called his wife. He slept in the cramped Bloommobile. When he woke up, he walked 10 yards and collapsed.

Staff writer David Brown contributed to this report.

David Bloom, above, "was able to relate to people in a very human way. . . . That reached through the lens," said NBC News President Neal Shapiro.Army medics rush NBC correspondent David Bloom, below, from his position outside of Baghdad after the 39-year-old collapsed yesterday. A blood clot in his leg ultimately led to a pulmonary embolism that killed the ambitious journalist.