It was a snag that U.S. officials had said they were braced for but appeared shaken by: When the American hostages assembled Friday at the Tahweita school near Beirut airport for what was billed as a bus ride to Syria and freedom, four of the 39 were missing.

As the American captives milled in the schoolyard, resembling a tour group with their baggage neatly arranged in two long rows, American network cameras filmed their spokesman, Allyn Conwell of Houston, as he called the roll at the request of a representative of the International Committee of the Red Cross.

Those who failed to respond were Robert G. Brown, 42, of Stowe, Mass.; Richard Herzberg, 33, of Norfolk; Jeffrey Ingalls, of Virginia Beach; and Robert Trautmann Jr., 37, of Laredo, Tex.

The four were believed to be part of a group taken off hijacked TWA Flight 847 in the midnight hours of June 15, during the plane's violence-marked second landing at Beirut. They reportedly were spirited away by radical Shiite gunmen of the pro-Iranian Hezbollah faction.

Speculation had focused since then on whether Shiite Amal militia leader Nabih Berri would be able to deliver the splinter group as part of any deal. Berri's men took control of most of the hostages away from the original hijackers, and he has served as key negotiator.

Three TWA crew members not present for the schoolyard roll, which took place in the early afternoon, Beirut time, joined the group later.

Members of the split-off hostage group were of special interest to the hijackers because they held papers identifying them as U.S. government personnel, or because they had "Jewish-sounding names," according to administration officials and eyewitnesses from Flight 847.

Trautmann was reported to be among those removed because his name sounded Jewish. He is Catholic. A land developer in Laredo, he and six other family members had been vacationing.

His father-in-law, Vicente Garza Jr., 53, is among the hostages who gathered in the schoolyard. The men's wives and three Trautmann children were released in the first days of the hijacking.

"The family is just doing everything they can to find out about Bob," said neighbor Judith Zaffirini at the Trautmann home late yesterday. Trautmann's parents, Bob Sr. and Podi, had already left for Frankfurt, West Germany, where the hostages were to be flown after their release, she said.

Brown, another missing hostage, was in the Mideast on a business trip. He has a wife and two daughters. Donna (Jill) Brown, his wife, was exhausted by the wait, family friend Marsha Soja said. "She feels emotionally drained. She wanted good news, and she's angry it's not over."

Herzberg, an insurance salesman for John Hancock Co., was honeymooning in Greece with his wife, Sue Ellen. She was released.

Ingalls has been described by friends as an outdoorsman who enjoys skiing. Before she learned of the glitch, his girlfriend, Nancy Moyer of Chesapeake, said, "I'm ready to fly. I'm getting all excited and I can't put it into words."

Some U.S. military personnel who had previously been held separately were present in the schoolyard. "They thought we were Marines," Stuart Dahl, 31, a U.S. Navy diver from Norfolk, told reporters. He added that his captors "put us in a safe area so we wouldn't hurt them."

Richard Testrake of Erie, Pa., brother of the flight's pilot, John Testrake, said, "They get our hopes up and, then, bang, down they go again."

He got a call from the State Department at about 3:15 a.m. saying the hostages were enroute to Damascus, he said. But when he called back to find out about reports that the hostages were still in Beirut, "they said, 'No comment.' "

At St. Margaret Mary Roman Catholic Church in Algonquin, Ill., the parish of 8 hostages who had been on a tour of the Holy Land, the morning had begun with high hopes which faded as the news filtered in. JoAnn Lazansky, wife of hostage George Lazansky, 53, a bank executive, attended a prayer service with her son, Tom.

Pam Watson, wife of hostage Tony D. Watson of Virginia Beach, said, "It makes me nervous. You get all the good news and then there's a hold up."

TWA has offered to fly one family member per hostage to Frankfurt.