(Pittsylvania County, Va.) – Gretna Middle School was placed under lockdown Tuesday afternoon after a telephone threat was received by school officials.

The incident was reported just before 1 p.m. That’s when the school’s resource officer was told that a man was headed to the school, armed with an assault rifle.

According to a news release from the Pittsylvania County Sheriff’s Department, the caller had learned his child was not in attendance Tuesday and was questioning the student’s absence. The caller’s estranged wife had earlier called the school, and authorities are now trying to determine if any threat was made.

The call came from Roanoke. Investigators contacted the caller and determined that he never left his home, which had been reported by his estranged wife.

One person was arrested during the lockdown for disobeying orders not to enter the school. He was charged with disorderly conduct and released on bond.

Gretna Middle, High and Elementary Schools were all placed under lockdown for about an hour and students were released to go home at the regular time.