A Frederick County, Maryland, student who tried to make mustard gas — and who brought what turned out to be bleach to school — has been charged with disrupting school activities and threatening mass violence.

According to the Frederick County Sheriff’s Office, the 14-year-old boy told deputies that he watched a social media video on how to make mustard gas, and said on Snapchat that he was planning to make the chemical agent at Urbana High School.

After authorities were alerted, they arrived with hazmat suits to the school on March 3. Students were evacuated to a nearby middle school and into school buses while first responders swept the building.

The boy will be treated as a juvenile and his identity will not be released. Frederick County Schools might take their own disciplinary action, according to a statement from the county Sheriff’s Office.

WTOP’s Alicia Abelson contributed to this report.