John W. Hancock, of the FBI's Memphis office, said the charred shell of the Chevrolet Suburban was found by local law-enforcement officials at about 1:30 a.m. Tuesday in a north Memphis industrial and residential neighborhood.

The FBI said the vehicle contained about 12 weapons including M-16 rifles, MP-5 rifles, as well as a shotgun, tear-gas equipment, ammunition and bulletproof vests, helmets and shields with agency insignia.

The unmarked vehicle belonged to SWAT agents from Little Rock, Ark., who were staying at the Budgetel Inn, on the east side of Memphis. They had driven up for a weeklong regional training exercise on terrorism involving more than 500 local and FBI personnel from field offices in Minneapolis, Baltimore and a number of Southern cities.

``When you have 500 people in one place, with the necessary amount of vehicles,'' Hancock said, ``the possibility of something like this happening is great.''

Nevertheless, the incident comes at a particularly inopportune time for the FBI. The agency has been embarrassed in recent months by criticisms of its once-vaunted criminal laboratory; by the case of Richard Jewell, whom the agency wrongly named as a suspect in the bombing at the Olympic Games in Atlanta, and other mistakes. Today, Director Louis Freeh is to testify before the Senate Judiciary Committee on bureau operations.

Late Tuesday afternoon, the FBI said the missing weapons and equipment had not been found. Hancock declined to comment on why the guns and ammunition had been left unguarded in the vehicle in a motel parking lot.

Local police said they had combed the neighborhood where the Suburban was found but have not found any discarded weapons. The FBI said such regional meetings are conducted about eight times a year around the country to teach local authorities proper procedures for dealing with major crises like the Oklahoma City bombing and the stand-off with the Freemen in Montana.