Children and teachers were allowed back into Oscar Mayer Magnet School in Lincoln Park after a "suspicious object" found behind the school was deemed not a threat.
Chicago Police bomb and arson units were called to the school, at 2250 N. Clifton, just after 8 a.m. Monday for an object that apparently looked like a hand grenade, police said.
Police later concluded the object was not an explosive, according to News Affairs.
Class was due to begin at 8:45 a.m., and faculty and students briefly were kept out of the school.
No injuries were reported.