Ribault High School, Ribault Middle School and Sallye B. Mathis Elementary were on lockdown Friday because of police activity in the area.
School officials said all students and teachers are safe.
The schools were put on lockdown at approximately 10 a.m. after several people ran on campus at Ribault High School without permission.
They were detained, Ribault High School Principal Christopher Jackson said.
The three schools are now on code yellow lockdowns as police investigate possible criminal activity off campus.
The lockdowns are expected to be lifted soon so students can go to lunch.
Action News Jax is working to learn more about the lockdowns.
Watch CBS47 at Noon for the latest.