The York town clerk’s office was on lockdown Thursday morning after employees found an envelope containing a suspicious white substance that turned out to be crushed diet pills.

Employees opening the mail around 10 a.m. found the substance and called the York Fire Department for help. The rest of town hall was evacuated while employees in the town clerk’s office were asked to stay where they were because they had been exposed to the substance but were not showing any symptoms, according to police Lt. Luke Ernenwein.

Firefighters were able to communicate with the employees through windows and doors during the roughly 30-minute wait for the arrival of the Navy hazardous materials team from the Portsmouth Naval Shipyard.

The hazardous materials team obtained a sample of substance and determined it was a dietary supplement called “Ripped Fuel,” Ernenwein said in a press release.

No one was injured during the incident.