NEW YORK -- Howard Lutnick, chief executive officer of bond brokerage Cantor Fitzgerald LP,didn't make it to work on time Tuesday because he took his son to his first day of kindergarten.

And thus, he was not counted among 700 New York-based employees of the company's World Trade Center headquarters who perished in the attack that started when American Airlines Flight 11, en route from Boston to Los Angeles, sliced through the north tower about 8:45 a.m. Tuesday.

Cantor is one of the world's largest fixed-income interdealer brokers. It resumed trading yesterday from its backup site in New Jersey, company officials said.

Of its more than 2,300 employees worldwide, about 1,000 occupied floors 101 through 105 of the World Trade Center's north tower. About 700 of those employees, including Mr. Lutnick's brother, who worked on floor 103, are believed to have perished. About 270 survived.

"I didn't go in early that morning," a teary Mr. Lutnick told ABC-TV's Connie Chung in a televised interview yesterday. "My little boy . . . it was his first day of kindergarten. . . . I took him for the first day of big boy school and because of that I was late to the office."

Mr. Lutnick said he was on the way into the building when all hell broke loose. He stood by the door grabbing people and asking them to call out their floor numbers as they ran out. Ninety-one was the highest number he heard before the other tower collapsed.

People were screaming and running out of the building and he saw the second tower collapse above him. "I turned around and ran," he said. "I was standing underneath the building like an idiot," he said. "I touched my eye. I couldn't see my hand. I could feel the particles in the air. . . . I was just standing there thinking that I can't believe it. . . . Four hours I walked. I just walked."

Mr. Lutnick said he spoke with two employees who were badly burned and hospitalized in critical condition and that he was praying for them "to pull through and be strong."

He said that Cantor employees in Los Angeles and London were on conference calls with employees in New York at the time of the attack and listened in horror as people screamed before lines went dead. "They couldn't go down, they couldn't go up," he said.

Mr. Lutnick said the incident has permanently changed him. "My view of business is different. I need to try to be successful in business so I can take care of . . . 700 families who are dreaming to find someone. . . . I have a different kind of drive. It's not about my family. I can kiss my kids tonight. But other people won't get to kiss their kids."

To that end, Mr. Lutnick posted his home telephone number on his company Web site and has been taking calls from relatives of his employees at all hours of the night. "Women are calling me . . . they don't know how to pay their mortgage and they don't know what they're going to do," he said.

About 200 other New York-based employees want to work, he said, because they want to stay occupied. "I think we are all pulling together with the view we want to make things happen for them. We need to take care of them."

"It's amazing," he said, of his employees. "Three hundred people lost all their friends. They lost the person to their left, the person to their right. They call me up and say: 'I want to go to work. . . . I can't stay home.' "

Near the end of the interview Mr. Lutnick, who cried at various points throughout, broke down and wept. "I have to . . . do something," he said, ". . . for the 700 families. Seven hundred families. Seven hundred families. I can't say it without crying."

The 56-year-old Cantor, a broker for other brokers, handled about one-quarter of daily trades in the $3-trillion (U.S.) government bond market. The firm is pivotal to the market, investors say.

"Cantor is indispensable," said Sean Dobson, president, CEO and head trader at Amherst Securities Corp. in Houston. "Even though these markets may be electronic, they are based on information and trust, which is gathered over the phone from people who you've worked with for years," he said.

Customers that want to do business must contact the firm through the London office, a spokeswoman said.