The chief flight attendant on the hijacked TWA Flight 847 said yesterday that passengers on the jetliner included four American marines, one who was "brutally beaten," and another who who was shot dead.

Uli Derickson of Newton, N.J., told reporters at a New York news conference that she believes the man who was slain by the terrorists on the plane was a 30-year-old marine, based on her inspection of the passengers' travel documents. Her report contradicts earlier statements by some of the released passengers that the dead man may have been a member of a Navy diving team. Pentagon officials said yesterday that some military personnel were aboard the plane, but refused to give details.

Derickson, one of four flight attendants who spoke at the news conference, described the initial takeover of the plane as "brutal" and said the hijackers shoved her against the wall and gave her "a karate chop" to her chest. She said they held grenades and were clenching the pins in their teeth.

In the early moments, Derickson said, one of the men pulled a pin from the hand grenade and held it in his mouth. "He dropped it on the floor, then made me pick it up and put it in his mouth."

Derickson said the hijackers "brutally beat up" two of the men believed to be marines and an American construction worker working for the U.S. Navy in Greece, because they were seen as "American emissaries."

After beating the man who Derickson said she believed was a marine named Robert Stetson, the hijackers shot him in the head and threw his body off the plane. "I don't know what provoked them," she said.

The official TWA passenger list shows no Stetson. The closest to that name is M.R. Stethem of Virginia. According to TWA officials last night, Stethem is unaccounted for.

Derickson said that hijackers later ordered her to pick out "the passports of passengers with Jewish-sounding names." Derickson said she did not select the passengers but handed all of the passports to the hijackers, who eventually selected six or seven passengers they believed to be Jewish.

The hijackers removed those passengers from the plane during one of the stopovers in Beirut and took them to an unknown location.

"She [Derickson] collected the passports and any discussion she had with them hijackers , she was trying to discourage them," said Sally McElwreath, a TWA spokeswoman. "If the name was . . . a so-called Jewish-sounding name, she would say, 'No, that's German, or that's Swedish.' She did not choose any of the passports."

Derickson said the hijackers also "told me to pick out the oldest and feeblest and the mothers and children," most of whom eventually were released.

She said that after the initial takeover, "we were treated well" by the hijackers.

Derickson, who said she is German, said she served as interpreter between two German-speaking hijackers and the crew in the cockpit.

Helen M. Sheahan, a TWA flight attendant from Washington, said "the reason I would say there was tremendous calm is the passengers were . . . an unusual group." She said everyone was ordered to sit "in the emergency position," with their heads between their knees for 10 of the 29 hours the attendants were held on the plane.

At one point, some of the passengers wanted to try to overpower their captors, according to Derickson, who said she urged "please don't do anything in midair."

In St. Louis, the Rev. Elmer Zimmermann, 88, whose son Benjamin is flight engineer on the plane, died Saturday after suffering a heart attack, according to United Press International.

"It was very frightening to have somebody as crazy as the two hijackers in complete control," said Dorothy Sullivan, a retired teacher from Aurora, Ill., who was released and arrived at O'Hare Airport in Chicago last night.

Frances Reynolds, of Chicago, said that when the hijacking began Friday, "I thought I'll be dead by the time I get home . . . . I heard them hitting people. They broke one woman's glasses. Her husband got up and one of them a hijacker said, 'Want it?' " Reynolds gestured with her hand, showing how the hijacker had brandished a grenade.

Isabella Carpio, a Filipino, one of the released passengers who spoke to reporters in Chicago, said the passengers were warned repeatedly to keep their heads on their flight tables, to remain silent and not look up. "I had been through World War II in the Philippines and I have experience in such situations. You feel more or less helpless."

For the relatives of many Americans on board the plane, there were mixed emotions as they learned that their daughters and mothers had been released, but that sons and fathers remained captive.

Steve Willett, 36, of Choupic, La., watched as his wife, Marsha, 32, and 9-year-old son, Joshua, were freed at one of the stops. He pleaded with captors who refused to release his elder son, Christopher, 17, according to his relatives.

"Christopher is very tall for his age," said the teen-ager's aunt, Gayle Willett, from the family's home. "They wouldn't let him go because he looked like he was a man, not a child."

But the hijackers relented Saturday afternoon and Christopher was the last of a group of 50 hostages released in Algiers.

Three honeymooning couples -- two of them from the Tidewater area of Virginia -- were among the families that were split.

Sue Ellen and Richard Herzberg of Virginia Beach were married two weeks ago. After her release, Sue Ellen Herzberg telephoned family members from Algiers Saturday night and said her husband had been taken off the plane while it was in Beirut and that she didn't know where he was.

"We're torn with mixed emotions," Sue Ellen Herzberg's father, Ted Deutsch, told wire services. "We don't know whether to be happy or sad at this time."

Michael and Judy Brown, who recently moved from Portsmouth to North Miami Beach, Fla., also were honeymooning.

Elaine Brown of Portsmouth, watched on television as her daughter-in-law Judy, 25, was released. Her son, Michael, 27, was not. "I'm hoping and praying that my son will get off," she said.

Staff writers Kevin Klose and Stephen Labaton contributed to this report.