A Pentagon SWAT police unit plans to practice live shooter scenarios, in which officers react to a purported gunman on the loose, in the Prince William County town of Haymarket on Tuesday, officials said.

The drills are scheduled to take place between 8 a.m. and 1 p.m. at the building known as the old Pace School, located at 14600 Washington Street . The building is owned by Quality Business Engineering, a defense-related federal contractor. A Prince William fire and rescue unit is also scheduled to join the drill.

Pentagon spokesman Tom Crosson confirmed the training exercise.

The front half of the building where the drills are scheduled to take place is unoccupied, said QBE chief executive Shawn Landry. St. Paul’s School, a small preschool, occupies the back part of the building.

Landry said he does not expect the drills to interfere with the school day. Police will be on hand to make sure all goes smoothly, officials said.

About 10 to 15 volunteers from Landry’s company plan to shoot chalk bullets at the Pentagon’s unit of about 15 officers during different shooter scenarios, Landry said.

“It gets the people who are protecting us some training,” Landry said. He said he was approached by the Pentagon after the building was used for fire and rescue exercises in recent months.

The Pentagon police department’s “Emergency Response Team” is responsible for the protection of more than 30,000 employees on the Pentagon’s expansive grounds, according to its Web site.