A 21-year-old college student has been arrested for threatening to “execute aproximately (sic) 16 white male students and or staff” at the University of Chicago, and then “any number of white policemen,” to avenge the fatal shooting of Laquan McDonald, according to a criminal complaint and affidavit filed in U.S. District Court in Chicago.

Jabari R. Dean, of Chicago, was arrested Monday and charged with transmitting a threat in interstate commerce, the U.S. Attorney’s Office for the Northern District of Illinois announced. According to the affidavit, Dean wrote in an online post that he planned to show up at the University of Chicago’s campus quad Monday morning armed with an assault rifle and two semi-automatic pistols and would “do my part to rid the world of the white devils.”

The University of Chicago canceled all classes and activities at its main campus on Chicago’s South Side on Monday, after the FBI informed the school that an unknown person had threatened gun violence against the campus community at 10 a.m. Monday.

An FBI special agent said in the affidavit that post was written by Dean, who threatened to kill approximately 16 white students and university staff members — “which is the same number of time (sic) Mcdonald (sic) was killed.”

Laquan McDonald, a black teenager, was fatally shot last year by a white Chicago police officer, who fired a total of 16 shots — all of the ammunition in his clip. Jason Van Dyke, a 14-year veteran of the police force, has been charged with first-degree murder in the fatal confrontation, and a newly released graphic video of the killing had sparked unrest in Chicago.

On Monday, federal authorities confronted Dean before the 10 a.m. deadline given in the post, and he was arrested without incident, according to the prosecutor’s office.

Dean is a student at nearby University of Illinois at Chicago, that school said in a statement.

The post was deleted, but authorities were given a copy of it, according to the affidavit. Dean, the document said, admitted to a federal investigator that he had posted it from his phone.

According to the Chicago Tribune, Dean “appeared in federal court Monday afternoon wearing a red UIC hooded sweatshirt and jeans, and kept his arms at his sides as he quietly confirmed that he understood the proceedings. He will be held in jail until Tuesday, when he is expected to be released to the custody of his mother.”

If convicted, Dean could face up to five years in prison, according to the U.S. Attorney’s Office.

The University of Chicago community was warned of the threat Sunday when school President Robert Zimmer sent an e-mail urging students and nonessential staff members to keep away from campus and instructing students in college housing to stay indoors. But the hour came and went without incident, according to the Chicago Sun-Times.

“Except for campus police and other security personnel in blue coats stationed on nearly every block,” the newspaper reported, “the University of Chicago’s Hyde Park campus was desolate Monday morning.”

Still, similar threats — and spasms of violence — have swept the country in recent months.

Zimmer said in his announcement that “based on the FBI’s assessment of this threat and recent tragic events at other campuses across the country,” officials had decided to shut down the school.

Last month, schools in Philadelphia were put on alert over a 4chan post that threatened campus violence. Days later, Eastern Kentucky University temporarily shut down when someone wrote “KILL ALL BY 10/8/15” on a bathroom wall.

Last week, Western Washington University canceled classes when someone on social media threatened minority students.

The threats followed a campus debate over an initiative to change the school’s mascot, Victor E. Viking, an angry-looking white character that has represented the school for nearly a century.

Some on campus argued that the mascot may be considered offensive to non-white students; others became angry over the claim. And the friction ignited a heated exchange on social media.

Similar incidents continued to emerge over the weekend.

Ohio State University police were called Sunday morning when a former employee vandalized school property and then shot and killed himself, authorities told the Columbus Dispatch.

On Sunday night, film students from Moorpark College in California were arrested when they triggered a panic on the 101 Freeway with replica weapons, according to the Los Angeles Times.

Colleges and universities have been on high alert since last month, when 26-year-old gunman Chris Harper Mercer opened fire at Umpqua Community College in Roseburg, Ore., killing nine people and wounding many others before taking his own life. Witnesses said that during Mercer’s “horrific act of cowardice,” he had singled out Christians when choosing whom to kill.

Students at the University of Chicago were preparing to return to school from the Thanksgiving holiday Sunday night when they got word about the threat. Zimmer, the university president, said all events at the Hyde Park campus would be canceled Monday, including those at the University of Chicago Laboratory Schools, the University of Chicago Charter School campuses, university libraries, the Quadrangle Club, as well as other campus facilities.

The University of Chicago Medical Center remained open for patients, “with added security measures,” Zimmer said.

On Monday afternoon, with a suspect in custody, Zimmer announced that “normal operations” would resume at the school Tuesday.

But, he said: “The University will leave additional security presence in place through the end of the Autumn Quarter.”

This story has been updated.