ELDORADO, Texas - More than 400 children, mostly girls in pioneer dresses, were taken into state custody from a polygamist sect in what authorities described yesterday as the largest child-welfare operation in Texas history.

The days-long raid on the sprawling compound built by now-jailed polygamist leader Warren Jeffs was sparked by a call to authorities from a 16-year-old girl who said that she was being abused and that girls as young as 14 and 15 were being forced into marriages with much older men.

Dressed in home-sewn, ankle-length dresses with their hair pinned up in braids, 133 women left the Yearning for Zion Ranch of their own volition along with the children.

State troopers were holding an unknown number of men in the compound until investigators finished a house-to-house search of the 1,700-acre property, which includes a medical facility, numerous large housing units, and an 80-foot white-limestone temple that rises discordantly out of the brown scrub.

"In my opinion, this is the largest endeavor we've ever been involved in in the state of Texas," said Children's Protective Services spokesman Marleigh Meisner, who said she also had been involved in the 1993 siege of the Branch Davidian compound in Waco.

The members of the Fundamentalist Church of Jesus Christ of Latter-Day Saints spent their days raising numerous children, tilling small gardens and doing chores. But at least one former resident, Carolyn Jessop, said conditions were not some idyllic replica of 19th-century life.

"Once you go into the compound, you don't ever leave it," said Jessop, one of the wives of the alleged leader of the Eldorado complex. Jessop left with her eight children before the sect moved to Texas.

Jessop, 40, said members of the community emphasized self-sufficiency because they believed the apocalypse was near. The women were not allowed to wear red - the color that Jeffs said belonged to Jesus - or to cut their hair. They also were kept isolated from the outside world.

Meisner said each child would get an advocate and an attorney. She predicted that if they ended up permanently separated from their families, they would face a difficult acclimation to modern life.

Tela Mange, a spokeswoman for the state Department of Public Safety, said that a criminal investigation was still under way and that charges would be filed if investigators determined children had been abused. Still uncertain was the location of the girl whose call initiated the raid.