Threatening graffiti found in three men’s restrooms led a Rochester, Mich., school to cancel campus classes, sports and cultural activities for two days.

Oakland University said it sent out a security alert Saturday after finding one threatening message, and officials said they found similar messages in men’s restrooms in two other buildings later that day.

The school didn’t reveal contents of the threats. But university Police Chief Sam Lucido told the Detroit Free Press that they referred to possible campus attacks on “4/14.”

That is the same date noted in threatening graffiti found twice this month in a freshman dorm at St. Xavier University in the Chicago area. Officials at the Catholic liberal arts college shut the school down indefinitely on Friday and told students to leave its campuses in Chicago and suburban Orland Park, Ill.

Lucido spoke Sunday with the head of security at St. Xavier, Oakland spokesman Ted Montgomery told The Associated Press. “I don’t think as of yet they’ve established any connection that seems reliable,” he said.

Lucido told the Free Press that the Oakland University threats didn’t target anyone specific, and that authorities believe the same person left all three threats.

The activities cancellation was in effect at the school for Sunday and Monday. Dormitories remained open, although Oakland University spokeswoman Michelle Moser said students were encouraged to go home if possible.

The public university has about 18,000 students in Rochester, about 20 miles north of Detroit.

St. Xavier spokesman Joe Moore said Sunday that students would be informed by e-mail, phone text messages and a school Web site of any decision to reopen.

“We’re hoping to open as soon as possible,” Moore said.

Elsewhere in the nation, schools are reporting an increase in false crime reports. Media attention and new campus alert systems established after the mass shootings at Virginia Tech are thought to be responsible.

In the past two months, at least three false reports have been filed on crimes at North Carolina college campuses. About a half dozen more have been publicized across the country within the past six months.

“For some people, it’s the attention-seeking. For others, it’s revenge. For still others, it’s the feeling of power they get by watching a college campus react,” said Daniel B. Kennedy, a professor in the Criminal Justice Department at the University of Detroit Mercy. “It’s like starting a fire, then sitting back and watching the commotion.”

False reports that trigger campus alert systems may not cut into the budget, but they can be costly when it comes to credibility, Capt. Jon Barnwell of the N.C. State University Police Department said.

Several conversations take place at NCSU before a message is sent out through the university’s campuswide alert system, Barnwell said.

“You’ve got to define your parameters of when you use it,” he said. “You’ve got the situation of the person who cries wolf … how long can you go before it’s construed as ‘Oh, this is a message from the Listserv, I’m gonna delete it,’ as opposed to ‘this is something I don’t get often, so I’m going to read it.”‘

On Wednesday, memorial services commemorating the nation’s deadliest shooting rampage will be held at the Blacksburg, Va. campus where 33 students and teachers were killed one year ago.