A Gainesville business that received a suspicious letter learned the threatening post was a false alarm.

Employees at Arrow Trucking discovered a powdery substance inside a piece of mail around 10 a.m. Thursday and soon called officers to investigate.

Hall County Fire Services recovered the letter around 11 a.m. and turned the evidence over to the Hall County Sheriff's Office, which requested help from the FBI.

Agents from the Joint Terrorism Task Force along with a U.S. postal inspector responded to the scene, tested the material and determined the substance was harmless, said Col. Jeff Strickland, Sheriff's Office spokesman.

The business was evacuated briefly while firefighters secured the letter. Normal operation resumed after the incident, which remains under investigation.

Strickland did not give details of the actual contents of the letter.