The CIA Accidentally Left 'Explosive Training Material' on a School Bus The bus continued to take kids to school.

 -- The Central Intelligence Agency accidentally left stable “explosive training material” in a school bus last week after concluding a routine training exercise.

The Loudoun County, Virginia, school bus unknowingly took elementary and high school students to and from school on Monday and Tuesday with the material under the hood of the bus.

On Wednesday, the CIA was notified that the explosive training material, while inert, was found in the bus during a maintenance check.

On Thursday the CIA said in a press release , that it had worked with local authorities to recover all of the explosives.

The Loudoun County Sheriff’s Department also issued a press release on the incident, calling the material “incredibly stable.”

“CIA and Loudoun County explosives experts have confirmed that the training material did not pose a danger to passengers on the bus,” the department said. “As a precaution, all buses that were used or were near the training exercise at the Briar Woods High School were further searched and nothing was found."

Wayde Byard, spokesman for Loudoun County Schools, told ABC News that a specialized blasting cap would be needed to detonate the explosives.

Principals in the school district called the families of the 26 students who rode that particular bus and an alert was sent to 80,000 students and staff, according to Byard.

Loudoun County Public Schools posted about the incident on Facebook Thursday.

Several people commented on the posting, asking why the training exercise used an active school bus instead of one no longer in use.

“CIA is a part of the Northern Virginia community. Many of our officers and their children live in the area. We will do whatever it takes to prevent this from happening again,” Dean Boyd, director of the CIA's office of public affairs, said.

Last week’s training exercise was for CIA K-9 units to practice detecting explosives.

During part of the training, material was hidden inside the engine compartment of the school bus, according to the Loudoun County Sherriff’s Department.

“At some point, a portion of the material from the container appears to have been dislodged from the container and fell into the engine compartment of the bus and was not recovered following the training,” the department said.

The CIA said it was taking steps to prevent this from happening again, like strengthening “inventory and control procedures in its K-9 program.”

The CIA K-9 training program will be independently reviewed.