COLUMBIA, Mo. -- A white college student suspected of posting online threats to shoot black students and faculty at the University of Missouri was charged Wednesday with making a terrorist threat, adding to the racial tension at the heart of the protests that led two top administrators to resign earlier this week.

Hunter M. Park, a 19-year-old sophomore studying computer science at a sister campus in Rolla, was arrested shortly before 2 a.m. at a residence hall, authorities said. The school said no weapons were found. Boone County prosecutors announced the criminal charge later Wednesday and recommended that he be held without bond.

Park, who is enrolled at the Missouri University of Science and Technology, was jailed in Columbia, about 75 miles (120 kilometres) to the northwest.

The author of the posts, which showed up Tuesday on the anonymous location-based messaging app YikYak and other social media, threatened to "shoot every black person I see." The posts followed the resignations on Monday of the University of Missouri system president and the chancellor of its flagship campus in Columbia.

Months of protests culminated in a tumultuous week on the Columbia campus.

Back in September, the student government president reported that people shouted racial slurs at him from a passing pickup truck, galvanizing the protest movement. Last week, a graduate student went on a hunger strike to demand the resignation of university system President Tim Wolfe over his handling of racial complaints.

Then more than 30 members of the Missouri football team refused to practice or play in support of the hunger striker. Those developments came to a head Monday with the resignation of Wolfe and Chancellor R. Bowen Loftin, the top administrator of the Columbia campus.

A message left by The Associated Press on Park's mother's cellphone was not returned. An AP reporter got no answer when he knocked on the door of the family's home in the affluent St. Louis suburb of Lake St. Louis.

By Wednesday afternoon, authorities were investigating a second threat on YikYak, this one levelled at the Rolla campus by someone saying, "I'm gonna shoot up this school."

When the first threat emerged, the school's online emergency information centre tweeted, "There is no immediate threat to campus," and asked students not to spread rumours.

Park has excelled academically in science. As a senior at Wentzville's Holt High School in early 2014, he was a member of the school district's robotics team when he won the honours division for a project titled "A Novel Method for Determination of Camera Pose Estimation Based on Angle Constraints."

The St. Louis Post-Dispatch reported that the project advanced to the Intel International Science and Engineering Fair in Los Angeles.

A spokeswoman for the Rolla school, Mary Helen Stoltz, said she did not know whether the university planned to take any action against Park over his arrest.

On Wednesday, student foot traffic in Columbia was light as freshman Megan Grazman was on her way to class. Although she said she felt safe, "There's nobody out. It's a ghost town. It's kind of eerie."

Yixiang Gao, a Chinese student from Shanghai, said he also felt safe, but he described the campus climate as "very heavy." He said his black roommate was not going to class.

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Associated Press writers Jim Suhr and Jim Salter in St. Louis and AP researcher Rhonda Shafner in New York contributed to this report.