A Hudson Valley teen is facing felony charges over allegations he wrote a letter which stated a plainclothes officer was going to walk around school with an assault rifle.

On Friday, Washingtonville police arrested a 16-year-old Washingtonville High School student for allegedly creating a fake letter.

The letter, which circulated among students and was posted to social media, indicated that the school was going to conduct a drill where a police officer would be dressed as a student and walk into the high school with an automatic rifle to teach students the proper way to respond to an assault at the school, police say.

According to police, the letter appeared on Washingtonville High School letterhead and was addressed to parents. Several parents called police fearing for the safety of their children.

Following an investigation, police charged a 16-year-old student with criminal possession of a forged instrument and forgery, both felonies. The boy was arraigned in Washingtonville Court and released to his parents.