In an emotional reliving on Friday of events that occurred almost three years ago, family members of the passengers and crew of the four planes hijacked to carry out the Sept. 11, 2001, attacks heard recordings of the phone calls made from the jets as they sped toward their doom.

The recordings, which captured some of the most chilling and heart-rending moments of the terrorist attacks, were the centerpiece of a 31/2-hour presentation in which Justice Department officials laid out what they know about the events on the planes before they crashed.

"Today was a very difficult day for all the families," said Debra Burlingame, whose brother, Charles, was the pilot of American Airlines Flight 77, which crashed into the Pentagon. "I was overwhelmed by the unbelievable courage of the passengers and crews of all four of these flights."

Citing the nondisclosure agreements they signed before joining the meeting, family members would not reveal the specifics they were told concerning the flights. The Justice Department fears that any leak of evidence could damage its case in the trial of Zacarias Moussaoui, the only person being tried as part of the Sept. 11 conspiracy.

But family members said the calls revealed individual acts of courage on all four flights, which carried 246 passengers and crew members and 19 hijackers.

"What we can categorically tell you is that there were many heroes on all four flights," said D. Hamilton Peterson of Bethesda, whose father and stepmother perished on United Airlines Flight 93, which crashed near Shanksville, Pa.

Since the attacks, partial transcripts of some calls have been released, and an excerpt of a recording of a call by flight attendant Betty Ong on American Airlines Flight 11, which crashed into the World Trade Center, was played at a January hearing of the independent commission investigating the attacks.

A commission staff report listed 11 such calls from passengers and crew members aboard the four planes.

Ong's 23-minute call, and a similar call by flight attendant Amy Sweeney on the same flight, provided airline officials with some of the first descriptions of the hijackings and their perpetrators. Sweeney told a ground manager in Boston the numbers of the seats where the hijackers had been sitting, among other details.

The last words of her call are believed to be "I see water and buildings. Oh, my God! Oh, my God!"

Moments later, the jet slammed into the North Tower of the trade center.

Sandy Dahl, whose husband, Jason, was the pilot of Flight 93, said many in the room sobbed as they listened to the phone calls.

"It was very hard," Dahl said. "We all held each other. . . . And we did learn a lot of things that we didn't know."