Police investigate Instagram comments that closed Oliver McCracken Middle School Wednesday

SKOKIE, Ill. (WLS) -- Police are investigating a threat posted to Instagram that shut down a middle school in suburban Skokie.

Skokie police officials confirm that on Monday they were contacted by McCracken Middle School and alerted to inappropriate and threatening communication received by students on social media. District 73.5 administrators and school officials are cooperating with police.

"We investigated the threat and passed it on to the school district, as a result, they made a decision to close the school," said Eric Swaback, crime prevention community relations.

Swaback says there is no specific information they can release about the content of the threat.

"We are still investigating how credible the treats are, there was nothing specific about a date or location but it was enough to warrant an investigation," Swaback said. "Federal authorities have been contacted by us, they are not actively involved but assisting us due to the fact that the social media outlets are out of our jurisdiction."

School officials felt it was in the best interest of students to cancel classes, sending a letter to parents notifying them of an investigation:

"This letter is to notify you that we are presently partnering with the Skokie Police Department to investigate a series of Instagram posts that have been shared with some sixth grade students. Some of our McCracken students are following anonymous users and/or allowing anonymous users to access their Instagram accounts. Safety is our first priority and we encourage you to monitor your child's Internet activity (including all digital devices) closely."

Sharon Morphew, a grandparent, is concerned about the timing of the school's closure.

"It happened on Monday, why did they wait until today to close the school, I am concerned," Morphew said.

The school has not said if it will resume classes Thursday.