SMYRNA, Ga. -- A code red at Campbell High School in Smyrna has now been lifted after an "unidentified intruder and threat."

The school sent a text alert to parents warning of the threat Monday afternoon and said police said the threat was made via walkie-talkie.

A Cobb County School district spokesperson said the code red was lifted and the situation is under investigation.

"Administrators learned of a rumor of a threat made by on campus at Campbell High School. After a thorough investigation by the Cobb County School Police and Smyrna Police Department, three persons have been detained. All students were and are safe at this time."

No additional details are available regarding the detained persons' involvement or whether or not they are students.

Parents are able to meet their students at the soccer field off Ward Street.