"Be prepared to die on 4/14" was scrawled on a bathroom stall in Regina Hall, a coed dorm on the Mount Greenwood campus, the Chicago Sun-Times reported.

Threatening graffiti had been discovered in the same bathroom stall earlier in the month, but the latest incident prompted officials to shut down St. Xavier indefinitely on Friday.

As a precaution, classes were canceled Monday at nearby Brother Rice High School, Mother MacAuley Liberal Arts High School and two elementary schools, Evergreen Park Southwest and Queen of Martyrs.

A spokeswoman for Chicago police said the Joint Terrorism Task Force is monitoring the situation and the city's office of emergency management has activated a 911 callback system to notify residents in the vicinity about precautions.

On Feb. 14 a gunman killed five people at Northern Illinois University in DeKalb, northwest of the city.