The ranch is located near the small town of Eldorado
Authorities in the US state of Texas have removed 52 girls from the ranch of the polygamist sect led by Warren Jeffs as part of a child abuse investigation.
Eighteen of the girls, aged between 6 months and 17, are in state custody. The rest are being found foster homes.
Jeffs, head of the Fundamentalist Church of Jesus Christ of Latter Day Saints, was jailed in November for 10 years for being an accomplice to rape.
He was convicted after he forced a 14-year-old girl to marry her cousin.
The self-proclaimed prophet is currently awaiting trial in Arizona on charges of being an accomplice to four counts of incest and sexual conduct with a minor stemming from two arranged marriages.
Officials from Texas Child Protective Services raided the sprawling ranch in Schleicher county, about 260km (160 miles) north-west of the Texan town of San Antonio, on Friday.
After the 52 girls had been removed and half of them interviewed by welfare officials, a spokeswoman announced that none would be returning to the ranch. Eighteen were legally removed into state custody.
"Those are the 18... who we believe have been abused, or are in imminent risk of harm or imminent risk of being abused. It would not be safe for them to stay in the compound for another day," Marleigh Meisner said.
"We're dealing with children that aren't accustomed to the outside world, so we're trying to be very sensitive to their needs."
Ms Meisner said the investigation had begun after Child Protective Services were called by someone who alleged a 16-year-old girl had suffered physical abuse.
A warrant for the search of the ranch sought records dealing with the birth of children by a 16-year-old girl and any records relating to her marriage to a 50-year-old man. Officials said the girl had not yet been found.
No arrests have been made and officials said the ranch's residents had been "assisting us in our search".
About 150 people are thought to live on the FLDS's 1,700-acre ranch in Eldorado.
The 10,000-strong sect, which dominates the towns of Colorado City in Arizona, and Hildale, Utah, split from the mainstream Mormon church more than a century ago.
Members believe a man must marry at least three wives in order to ascend to heaven. Women are meanwhile taught that their path to heaven depends on being subservient to their husband.
Polygamy is illegal in the US, but the authorities have reportedly been reluctant to confront the FLDS for fear of sparking a tragedy similar to the 1993 siege of the Branch Davidian sect in Waco, Texas, which led to the deaths of about 80 members.