Carl Sandburg High School in Orland Park went on soft lockdown for a couple hours this morning.
Extra police stood guard as classes let out this afternoon.
Students and staff spotted two former students near an open locker.
Officers searched the building, but the pair slipped out before they arrived.
Under a soft lockdown, classes continue but no one changes rooms.
Police found the intruders in a nearby parking lot.
They’re charged with criminal trespassing.