A private security guard who officials say accidentally wounded a student during a school shooting in Highlands Ranch that left one teen dead wasn't supposed to be armed, an online news outlet reported.

Emails obtained by The Colorado Sun show STEM School Highlands Ranch had requested an unarmed guard from BOSS High Level Protection about a year ago.

In a statement, STEM School Highlands Ranch said it didn't know the guard was armed until the shooting occurred May 7 on the K-12 campus. In addition to the fatality, eight students were wounded. Two teenage suspects were arrested.

“While it is more common to have armed security personnel at high schools, it is uncommon at elementary schools,'' the statement issued Aug. 26 said. “Given the diverse population at our school, we made the decision to request an unarmed guard in an effort to balance these different interests.''

Boss High Level Protection declined to comment to the Sun. The company referred questions from The Associated Press to Chief Operating Officer Grant Whitus, who did not immediately return a call.

The company and its lawyer, Robert Burk, have previously credited the guard with preventing more casualties at the school. The guard's actions have been under review by a special prosecutor since the shooting.

Court records say the guard mistakenly fired two rounds at a sheriff's deputy in the chaos and one bullet passed through a wall and hit a female student in a classroom. The guard later captured one of the shooting suspects.

Kendrick Castillo, 18, was killed in the shooting while trying to subdue one of the two teenagers charged in the attack.

The school had hired a private guard for the school year because of a dispute with the Douglas County Sheriff's Office over the duties of a previous dedicated school resource officer.

This school year, a resource officer from the sheriff's office is assigned to the school, and it will also use private security, including off-duty police officers. The school declined to say whether its private security guards will be armed.

The school will not use BOSS because of the pending review, but the emails obtained by the Sun show the school asked the company in July to recommend another company.