Four people were detained Tuesday after they trespassed on the Douglass High School campus, forcing it to be placed on lockdown, Atlanta Public Schools officials said.

Officers found no weapons on the people, spokeswoman Pat St. Claire told The Atlanta Journal-Constitution in an emailed statement. The school system was alerted to the intruders by students.

St. Claire said no one was harmed during the incident.

“(The Atlanta Public Schools Police Department) is currently investigating the situation and working in collaboration with Atlanta Police and the Fulton Sheriff Department,” she said in a news release. “APSPD officers stayed on site to ensure a safe dismissal for students and staff ... The safety and security of our students and staff is our priority.”

No other details were released.

In other news:

Teen Trying To Mimic Stunt Killed By Train