Eastern Kentucky University police and other authorities are interviewing "people of interest" in a graffiti threat that has shut down the Richmond campus for three days.
According to a campus update, the people were identified through the school's tip line. They are not yet considered suspects.
EKU is offering a $10,000 reward for information that leads to any arrests. Authorities would not release any information about the people they are speaking with.
A custodial worker found the graffiti in a bathroom Sunday in the Powell Building. The graffiti said: "KILL ALL BY 10/8/15 THIS BU OOP." Police have not said what "BU OOP" might be referring to.
During an interview Thursday morning on WEKU radio, university President Michael Benson said the decision to close school Wednesday was because of increasing fear and social media uproar, not because of more specific threats.
"Once they get agitated, it's really tough to dial that down," he said of students. "But in the aggregate, the chatter ... we felt the best thing to do was shut down for a couple of days."
Benson said the decision had nothing to do with the fact that fall break will be Monday and Tuesday. Classes won't resume until Wednesday.
Bryan Makinen, EKU's director of public safety, said in the radio interview that university officials didn't think this incident was related to similar threatening graffiti found in a bathroom in February.
"The two do not appear to be linked in any way," Makinen said.
The school has received about 75 tips, and authorities said they hoped there would be more.
EKU police have sought help solving the case from the FBI's Joint Terrorism Task Force, Kentucky State Police, Richmond police, the Madison County Sheriff's Office and Berea police. Police departments have increased patrols on campus.
The incident has caused a number of disruptions, including the cancellation of a show Wednesday night at the EKU Center for the Arts. Officials moved a Thursday night home football game to Toyota Stadium at Georgetown College, and an EKU home women's soccer game against Southeast Missouri was moved to Transylvania University's Pat Deacon Stadium, EKU officials said.
Officials said increased security would continue after classes resume Wednesday.
Callers to the WEKU program asked about copycats who could continue to terrorize the campus.
"We're going to take each threat very, very seriously; we're going to make an example that this will not be tolerated," said Gary Folckemer, EKU director of emergency management. "We have to stem this now."