OAKVILLE, Mo. – Officials have lifted a lockdown at Oakville High School in south St. Louis County after investigating a threatening message on school grounds.

District officials did no immediately disclose information on the threat, but tell FOX 2 that police and school administrators are investigating it. All students and staff are considered to be safe.

“During a lockdown students remain locked in their classrooms or other safe location. Nobody is allowed to enter or exit the school building until police provide an all clear,” said the Mehlville School District on the lockdown.

Parents are told not to pick up students until further notice from the district.

Additional details are limited at this time. FOX 2 will update as more information becomes available.