CHICAGO (CBS) — Classes were cancelled on Monday at a Catholic school in west suburban Glen Ellyn, after racist and threatening notes were found at the school and a nearby public high school.

Glen Ellyn Police said officers were called to St. Petronille School and Glenbard West High School to investigate several notes found on school grounds.

Glenbard Township High School District 87 spokeswoman Peg Mannion said stickers containing racist and derogatory statements were found around campus outside Glenbard West. One of the stickers contained a threat.

Police declined to reveal the contents of the notes, but Mannion said officials determined there was no immediate safety risk to the school or students.

St. Petronille decided to cancel classes on Monday. However, Glenbard West remained open.

Police and the school district were investigating.

“We are committed to investigating any and all incidents involving any criminal acts, particularly at our schools. Those responsible for this activity will be aggressively pursued and brought to justice,” Glen Ellyn Police Chief Philip Norton said in a statement.

Anyone with information about the notes should call Glen Ellyn police at 630-469-1187 or the Glenbard West hotline at 630-942-7406 to file an anonymous report.

“We ask students to notify a trusted adult if they hear about any planned or potential disruptive behavior. See something, say something,” Mannion stated in an email.