No shots were fired but students were told to get on the floor and all doors in the complex that combines Banks High School, a middle school and elementary classrooms, were locked as a precaution.
School superintendent Marilyn McGlasson said a middle school teacher was walking across the school grounds when he saw a police officer pursuing a man carrying either a shotgun or a rifle.
"The cop yelled 'Weapon!'" McGlasson said. "The teacher notified the district office and within 15 to 20 seconds all three schools were in complete lockdown."
An armed man was taken into custody a short time later and was being questioned, said Marlene Gaskins, spokeswoman for the Washington County sheriff's office.
"We still have the schools on lockdown until we make sure he was alone and there's no other danger to the students," Gaskins said.
She had no other details on the man.