SPRINGFIELD, Mo. (AP) — Springfield police are investigating reports of three alleged rapes at Missouri State University.

The Springfield News-Leader reports that four reported rapes triggered campus crime alerts from late August to early October.

Police spokeswoman Lisa Cox says the department’s Special Victims Unit is investigating three of the incidents. She says the investigating into a fourth incident has been suspended because of a lack of cooperation.

Cox says in the remaining cases, the alleged suspects and victims knew one another, and there’s no obvious link between any of the cases.