The female sect members wear distinctive long gowns
Officials in Texas have found signs of injury among children removed from a polygamous sect and are checking for possible sexual abuse of boys.
A judge ordered the removal of 464 children last month as officials investigated whether underage girls had been forced into marriage and sex.
A state welfare official said 41 of the children had broken bones or previous fractures, without giving more details.
The sect, which has Mormon roots, says the state is trying to mislead people.
It was raided on 3 April amid reports that a 16-year-old girl had been physically and sexually abused.
Detectives are looking for evidence of a marriage between the girl and a 50-year-old man.
Authorities believe that of 53 girls aged between 14 and 17, 29 are already mothers.
The number of children placed in protective custody has gradually risen, with a baby born to one young mother on Tuesday becoming the 464th.
The Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS) split from the mainstream Mormon Church more than a century ago.
Investigators found "historic physical injuries and fractures" among the children, said Carey Cockerell, head of the Texan department of family and protective services.
"Some of the fractures have been found in very young children," he told state lawmakers on Wednesday.
Mr Cockerell did not say what investigators believe may have caused the injuries.
He added that, based on "journal entries" and interviews, his agency was investigating possible sexual abuse of young boys at the ranch.
The official refused to speak to reporters after his appearance before the Texas Senate health and human services committee.
However, a spokesman for the agency, Patrick Crimmins, later stressed that it had not yet been determined whether the injuries found in the 41 children were "due to abuse or neglect or were just childhood accidents".
Lloyd Barlow, onsite doctor at the Yearning for Zion ranch where the sect was based, said he had been caring for a number of FLDS children with broken or fractured bones at the time they were removed.
"Probably over 90% of the injuries are forearm fractures from ground-level or low-level falls," he was quoted by The Associated Press as saying.
"I can also tell you that we don't live in a community where there is a pattern of abuse."
Mr Cockerell's speech was bitterly attacked by FLDS representatives.
On the suggestion that boys had been abused, FLDS lawyer Rod Parker said there was no evidence, and it was "irresponsible" and "unethical".
"Where the heck did that come from, anyway?" asked FLDS member Willie Jessop.
"Are they just pulling this stuff out of the air without having to prove the allegation or what?" he was quoted as saying by the Deseret News.
Mr Parker accused Mr Cockerell's agency of mounting a "PR campaign to attack the parents with highly inflammatory implications".
Agency spokesman Patrick Crimmins dismissed the allegation as "ridiculous", saying Mr Cockerell had merely been reporting to state senators at their request.
The legal age of sexual consent in Texas is 17 and polygamy is illegal in the US.
The girl at the centre of the investigation is reported to have been beaten and raped by her older husband, and to be pregnant again eight months after giving birth to her first child when she was 15.
Officials say some of the FLDS girls may have had babies when they were just 13 years old.
FLDS members are taught that a man must marry at least three wives in order to ascend to heaven, and that women must be subservient to their husbands.
Members live in large extended families, making it hard to determine exact parenthood, and the state is using DNA tests in its investigation.
The FLDS denies forcing young girls into polygamous marriages.