This is a developing story. Check back for updates.

High School was declared “all clear” after a lockdown Friday morning. School has dismissed for the day with no further incident.

Officials received a report of a gun, but nothing was found after an extensive search, Superintendent Chris Gaines said.

Police said that a gun could have been on campus Thursday in response to threats made on social media from one student to another. Police believe all involved are juveniles.

In a letter to MHS parents, Principal Denise Swanger said that just after school started, a student with personal knowledge reported to a school administrator that there was a gun on campus.

The district immediately contacted the St. Louis County Police Department, and the campus went on “soft lockdown” about 7:30 a.m.

During a soft lockdown, students remain in their current classroom and may only move around the building under the supervision of a school staff member.

During the soft lockdown, the police searched the school grounds. Searches revealed there were no weapons on the property. At about 9:30 a.m.,  the soft lockdown was lifted and students moved to their next class.

St. Louis County Police informed the district that the gun in question was recovered off campus. The police continue to investigate and were present on campus throughout the day.

“I want to thank our teachers and support staff for the leadership they provided students and their flexibility with their instruction today,” Swanger wrote. “I also want to thank our students for their understanding, calmness and cooperation. Student safety is our top priority, and we will always take all reports and threats seriously. If you have any questions, please call me at (314) 467-6000.

Read Swanger’s entire letter below:

Thank you for your cooperation and flexibility today as we worked to ensure everyone’s safety. I wanted to send you more information about what happened at Mehlville High School this morning.

Just after school started, a student reported there was a gun on campus. We immediately contacted St. Louis County Police and our campus went on soft lockdown. During a soft lockdown, students remain in their current classroom. Students may only move about the building under the supervision of a school staff member. During the soft lockdown, the police searched the school grounds. Searches revealed there were no weapons on the property. At about 9:30 a.m. our soft lockdown was lifted and students moved to their next class.

St. Louis County Police have informed us that the gun in question has been recovered off campus. The police continue to investigate and will be present on campus throughout the day.

I want to thank our teachers and support staff for the leadership they provided students and their flexibility with their instruction today. I also want to thank our students for their understanding, calmness and cooperation. Student safety is our top priority, and we will always take all reports and threats seriously. If you have any questions, please call me at 314-467-6000.

Sincerely,

Dr. Denise Swanger
Principal
Mehlville High School