Chicago police responded to the call at Dunbar Vocational Career Academy, which is part of the Chicago Public Schools district, in Bronzeville.
A 16-year-old girl and 16-year-old boy were both taken into custody.
SEE ALSO: 7 kids charged after woman, children beaten, seriously hurt near South Side CPS school, police say
The girl was charged with aggravated battery of a peace officer, CPD said.
The principal sent a community letter out Wednesday night, assuring parents that everyone was safe, and that classes would go on as scheduled on Thursday.
"We will continue striving to help our students reach their full potential and exemplify our core values both in the classroom and in their extracurricular pursuits," the note said.
INTERACTIVE SAFETY TRACKER | Track crime and safety in your neighborhood