Police arrested a 19-year-old white man on Wednesday on suspicion of making threats on social media to shoot black people at the University of Missouri's main Columbia campus, just two days after the school's president and chancellor stepped down following protests over their handling of reports of racial abuse.
Tensions at the campus are still running high after the resignations on Monday, with a greater-than-usual police presence and several students leaving the area saying they felt unsafe.
Police arrested suspect Hunter M Park in Rolla, Missouri, which is about 150km south of Columbia, at about 1.50am local time.
Mr Park is a sophomore at Missouri University of Science and Technology (S&T) in Rolla, which is part of the University of Missouri system, according to a spokeswoman at the Rolla campus. He is studying computer science.
Police said the suspect's threats had circulated on social media, including Yik Yak, where an anonymous post tagged "Columbia" late on Tuesday read: "I'm going to stand my ground tomorrow and shoot every black person I see."
“Some of you are alright. Don’t go to campus tomorrow,” another post read. “We’re waiting for you at the parking lots,” said a third post. “We will kill you.”
Yik Yak is an anonymous social media app that allows users to create and view posts within a five-mile radius. Yik Yak spokeswoman Hilary McQuaide said the company worked with police to identify Mr Park, saying it may do so when a post poses a risk of imminent harm.
"Threats of violence of any kind are not tolerated," said Cheryl Schrader, Chancellor of S&T, in a statement on Wednesday.
“We will take every threat seriously and act on them appropriately to protect our campus community,” Ms Schrader added. The school had not taken any action against Mr Park as of Wednesday afternoon.
Mr Park is from the St Louis suburb of Lake St Louis, Missouri, according to jail records. His parents could not be reached to comment.
He was arrested at an S&T residence hall by university police under Missouri law which prohibits communication of a life-endangering threat to at least 10 people. He was transported to Columbia and is being held at the Boone County Jail on a $4,500 (€4,190) bond.
Mr Park’s initial arraignment at the Boone County Courthouse is set for Thursday afternoon, according to a spokesman for the jail. No attorney was listed for him in the jail records.
On Twitter on Wednesday morning, the hashtags #PrayForMizzou and #BlackOnCampus were trending in the US, and many posts highlighted the anonymous threat on Yik Yak. “Mizzou” is the colloquial name for the University of Missouri.
Despite a heavier-than-normal police presence on campus, a few students decided to return home because they felt unsafe, students told Reuters.
University authorities said classes were operating on schedule. However, some professors, acting individually, cancelled classes. Other teachers gave students the option of not attending classes.
Bradley Smith, a graduate instructor of English, took to Facebook on Tuesday night to cancel his class.
“By holding class at our regular time, I would be forcing my students who do and probably should feel threatened, to implicitly disobey me in order to protect their lives by not attending my class,” he wrote.
Some students expressed frustration and anger at the school for not officially cancelling classes on Wednesday and downplaying the threat, students told Reuters.