An Arlington County police officer used a Taser on a cafeteria manager at an elementary school Wednesday after the school employee had an altercation with an administrator, police and school officials said.

The incident occurred in a kitchen office at Barcroft Elementary School about 11:15 a.m. after the administrator called police to report threatening behavior by the employee, said Dustin Sternbeck, an Arlington police spokesman. The school, about two miles west of Arlington National Cemetery near Route 50 and South George Mason Drive, was locked down when police arrived.

Sternbeck said the woman told police that she had a gun, and when she reached inside a bag, one officer jolted her with a Taser.

Officers did not find a gun but did find a knife in the bag, he said.

Schools officials declined to press charges against the employee. Police issued a mental detention order and the woman was taken to a hospital for psychological evaluation, Sternbeck said.

Schools officials emphasized that students were safe and did not witness the altercation between the cafeteria manager and the school administrator or her interaction with police. They declined to provide detailed information about the incident, saying it is a personnel matter.

“It was not around kids,” said Linda Erdos, spokeswoman for Arlington public schools. “It was not around classrooms or anywhere that kids are in the building.”

A letter sent home to parents from Barcroft said that the school was locked down only as a precaution.

“Within five minutes, the employee was removed from the school and the lockdown was lifted,” the letter said.