DRACUT -- A teacher's discovery of a "non-specific" threat written on a wall of a girl's bathroom at Dracut High caused administrators to order a temporary "soft lockdown" of the school for almost two hours Friday morning, Superintendent Steven Stone reported.

"Following existing procedures, the school entered into a soft lockdown, which meant keeping the kids in the classrooms they were at for a period of time, while Dracut police investigated," Stone informed the Sun after school on Friday.

Several police officers arrived at the school at about 9:30 a.m. to conduct an investigation and see to the safety of the students for the duration of the lockdown. Police and the school's staff's gave the go-ahead to resume its normal schedule by 11:30 a.m.

"Administrators at at the high school should be complimented for their management of the situation," Stone said.

In a message posted at 3 p.m. on the Dracut Public Schools online homepage, Stone informed the community "Dracut High School has returned to normal operations," he wrote. "Dracut Police will remain on site and will continue to investigate with the help of the school administration."

Stone said because it's an open investigation, the authorities are not publicly releasing the contents of the written threat.

The perpetrator, if caught, would be at guilty of a vandalism charge at the very least, he said.

"It'd be against the student handbook rule on vandalism to write anything at all on the wall," the superintendent said.

Follow John Collins on Twitter at johncolowellsun.