(JTA) — The white powder sent in a letter to the Jewish community center in Boulder, Colo., was “benign” and not harmful to humans, the Boulder County Sheriff’s Office determined.

A Boulder synagogue, Congregation Har HaShem, also reported that it received a similar letter on Monday.

The JCC evacuated its building after an employee received the threatening letter. The Sheriff’s Office said the letter, opened Monday morning, said “your [sic] have enemies,” several local media outlets reported.

Employees who came in contact with the letter had been put under quarantine. The local health department, fire department and Hazmat team responded.