Fairfax County Public Schools is investigating the system’s seclusion and restraint procedures, following a report that use of the controversial practices is underreported.

Students at some schools in Fairfax, home of Virginia’s largest school system, are routinely secluded, or involuntarily confined, according to a report on WAMU-FM. The station identified hundreds of cases that school system officials failed to report to the federal government.

“We know that parents trust schools to provide an environment in which students can learn and grow led by kind and caring professionals,” Superintendent Scott Brabrand said in a statement. “We want to ensure that all school-based personnel trained in the use of seclusion [and] restraint understand the appropriate use of the procedures.”

The practices are prohibited in Fairfax unless “there is a dangerous situation,” with seclusion or restraint necessary to protect the student or others, Brabrand said. The school system’s investigation will include parental notification, how data is collected and reported, and staff training.

Seclusion and restraint, measures that prevent students from moving freely, have drawn scrutiny for decades and disproportionately affect students with disabilities.

The practices have resulted in injury and, in the most severe cases, death, according to a 2009 federal study that examined the measures dating to 1990.

Last year, The Washington Post reported instances of seclusion in Loudoun County Public Schools that parents say endangered their children.

The Virginia Department of Education reviewed the Loudoun system’s seclusion and restraint policies and found “no evidence of systemic failure” to comply with those guidelines, which the department said aligned with state guidance, according to an August report.

Parents maintained that the treatment their children were subjected to in Loudoun was indefensible.

Virginia lawmakers in 2015 directed the state to adopt regulations on seclusion and restraint in public schools. Proposed regulations are undergoing review and a public hearing is scheduled for Thursday in Richmond.

Federal laws don’t regulate how seclusion is employed in schools, but government officials recommend its use only when students pose a physical threat to themselves or others. Seclusion should end once the danger subsides, the federal government advises.

The U.S. Education Department said in January that it would work with schools to reduce incidents of improper seclusion and restraint of students with disabilities.

In the 2015-2016 school year, more than 36,000 students nationally were subjected to seclusion, federal data shows. Nearly 86,000 more were restricted from moving freely by a school worker holding the child or by being immobilized by handcuffs or other restraints.

Experts and parents say underreporting masks the frequency of seclusion and restraint.

The WAMU report said students were secluded or restrained in Fairfax nearly 2,000 times between 2015 and 2016. At one elementary school, a parent told the news station, seclusion rooms are built like Russian nesting dolls, with rooms contained within rooms. Students with the most severe behavior issues were placed in the innermost room, the parent said.

Diane Cooper-Gould, president of Fairfax’s special education PTA, said some members of the group have experiences similar to those described in the WAMU report. Several families and teachers, she said, have contacted the group “fearful and in pain.”

She said she was encouraged by Brabrand’s decision to evaluate the school system’s use and reporting of seclusion and restraint. The special education PTA met with Brabrand this week and plans to follow the review closely.

“The fact that students with disabilities are disproportionately disciplined and restrained and secluded nation-wide is a societal problem that must be addressed as a matter of civil rights,” Cooper-Gould said in a statement.

Fairfax County School Board Chairwoman Karen Corbett Sanders said the panel will determine the next steps on the district’s seclusion and restraint practices based on Brabrand’s findings.

She said she had never heard from constituents about the school system’s seclusion practices but, after learning about the concerns, felt it was an “area that has not been as transparent as it should be.”

“We’re committed to ensuring that we have a caring culture and that we understand what has been done, what is being done and what we need to do in the future,” Corbett Sanders said.