A grandmother in Virginia has been arrested after authorities said she failed to cooperate with Child Protective Services during an investigation into the welfare of her four grandchildren, whose whereabouts were initially unknown.

Shirley Williamson, 52, was taken into custody after police and social workers were unable to locate the children following their placement in her care, according to the Fredericksburg Police Department.

The case began on April 6, when officers responded to a home in Fredericksburg to conduct a welfare check on four children. During that visit, authorities learned that the children’s mother, 28-year-old Kierstan Randall, had an active arrest warrant out of Stafford County.

Randall was subsequently arrested and booked into the Rappahannock Regional Jail without bond, police said.

Before being taken into custody, Randall placed the children with an adult at the home. Investigators later confirmed that Williamson, the children’s maternal grandmother, assumed custody of them.

After receiving information from a third party, officers filed a report with Child Protective Services, prompting an effort to locate and check on the children. Authorities said CPS repeatedly attempted to contact Williamson but was unsuccessful.

“Detectives and social workers both worked diligently to get the maternal grandmother to cooperate with authorities,” police said in a statement.

Because officials could not confirm the children’s safety or location, the four minors were entered into the system as missing.

Police said the situation did not meet the criteria for a Amber Alert or a Codi Alert, noting that there was no indication the children had disappeared under suspicious circumstances or were believed to be in immediate danger of serious harm.

On April 9, CPS obtained a removal order for the children. Authorities also secured arrest warrants for Williamson on charges including violation of a court custody order and contributing to the delinquency of minors by allegedly keeping the children outside the Commonwealth of Virginia.

Williamson later turned herself in to authorities and is currently being held without bond.

In an update, police said the children were located and are now in the care of Child Protective Services in West Virginia.

Authorities have not released additional details about how long the children were unaccounted for or where they were found.