COLUMBIA, Mo. (AP) – A University of Missouri student is accused of a campus threat posted on social media.

The university says the 18-year-old student was arrested Monday and later released on $4,500 bond. Formal charges had not been filed by midday Tuesday.

The student is accused of making a threat on the social media site Yik Yak. University police have not disclosed details, but interim chancellor Hank Foley says in a statement that the threat was not believed to be credible.

It was the second threat against the university on Yik Yak since November 9, when racial unrest led to the resignations of the Columbia campus chancellor and university system president. A student at Missouri University of Science and Technology in Rolla was arrested on November 11.