CHICAGO (AP) — Federal authorities said an online threat that led the University of Chicago to cancel classes Monday targeted whites and was motivated by the police shooting of a black teenager, video of which was released last week and sparked protests.

Jabari R. Dean, 21, of Chicago, threatened to kill 16 white male students or staff at the school on Chicago’s South Side, according to the criminal complaint.

Dean, who is black, was arrested Monday morning. He did not enter a plea later in the day on a charge of transmitting a threat in interstate commerce in court. Dean is a freshman studying electrical engineering at the University of Illinois at Chicago, and wore a red sweat shirt emblazoned with the name of that school at the hearing.

The threat was posted Saturday, just days after the city released a video of Officer Jason Van Dyke, who is white, shooting 17-year-old Laquan McDonald, who was black, 16 times.

Van Dyke is charged with first-degree murder, and his bond was set for $1.5 million on Monday. That means Van Dyke needs to pay $150,000 to be released, and Van Dyke’s attorney said he was hopeful his client could be released in the “very near future.”

Authorities said Dean posted online from a phone that he would “execute approximately … 16 white male students and or staff, which is the same number of time (sic) McDonald was killed” and “will die killing any number of white policemen that I can in the process.”

The criminal complaint, released by the U.S. attorney’s office in Chicago, said someone tipped the FBI on Sunday to a threat that was posted on a social media website. The FBI was unable to find the threat online, and was provided a screenshot by the person who reported the threat.

That led them to Dean, who admitted to FBI agents that he posted the threat and took it down shortly after posting it, the complaint said. Despite the threat mentioning three guns, a prosecutor said Monday that Dean did not appear to pose a threat. The complaint did not say whether Dean possessed any weapons.

The University of Chicago, where President Barack Obama taught law, first alerted students and staff Sunday night about a threat that mentioned the quad, a popular gathering place, and 10 a.m. Monday.

The University of Chicago statement urged faculty, students and non-essential staff to stay away from the Hyde Park campus through midnight Monday and told students in college housing to stay indoors. The cancellations of classes and activities affected more than 30,000 people, though the University of Chicago Medical Center was open to patients.

The normally bustling campus was almost desolate Monday morning as Chicago Police Department and campus security vehicles patrolled streets. Security staff guarded campus walkways, including the quad mentioned in the threat. The time mentioned in the threat came and went without incident.

The university had said the decision to close was taken following “recent tragic events” at other campuses nationwide. On Oct. 1 at Umpqua Community College in Roseburg, Oregon, a gunman opened fire and killed nine people. Other shootings have happened in Arizona and Tennessee.

Students closed their books, shut down their laptops and hurried home Sunday when the school first alerted people to the threat, according to student body president Tyler Kissinger.

“I work in the campus coffee shop and when people got the notice (announcements and online) they really cleared out of here immediately,” the 21-year-old senior said.

Junchen Feng, who’s pursuing a doctorate, said the threat raised his awareness about gun violence in Chicago and beyond.

“For the first time I was thinking about people who live in Syria, Afghanistan, Pakistan … where they live under constant threats of death and violence,” said the student from China, who planned to spend the day at home and in a campus building that was a five-minute walk away. “It’s a mindset that we just don’t have.”

Police have said that McDonald was carrying a knife and an autopsy revealed that he had PCP, a hallucinogenic drug, in his system. Cook County State’s Attorney Anita Alvarez said last week in announcing the first-degree murder charge against Van Dyke that the 3-inch blade recovered from the scene had been folded into the handle.

In the audio-free video, McDonald can be seen walking down the middle of a four-lane street. He appears to veer away from two officers as they emerge from a vehicle, drawing their guns. One of the officers, Van Dyke, opens fire from close range. McDonald spins around and crumples to the ground. The officer continues to fire.

Van Dyke’s attorney, Dan Herbert, maintains that Van Dyke feared for his life, acted lawfully and that the video does not tell the whole story. He told reporters Monday that Van Dyke “absolutely” can defend his actions in court and that the officer is “very scared about the consequences he is facing.”

Alvarez said last week that she had decided a few weeks earlier to charge Van Dyke with murder and was planning to announce charges in a month. But knowing the intense public anger that the sight of the “chilling” video would generate, she announced the charges before the video’s release in an effort to encourage calm.

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Associated Press writer Greg McCune contributed to this report.