EDITOR'S NOTE: This story has been updated with additional information and comments.
Police were present at Du Quoin schools on Monday after a 17-year-old Du Quoin High School student was charged Sunday with making what police call a vague threat.
Du Quoin Police Chief Les Vancil said the threat, made on social media, was vague and referenced the Sandy Hook shooting in Connecticut.
He said it did not detail how an attack might be carried out.
The student, who has not been identified because he is considered a juvenile, has been charged with disorderly conduct, a Class 4 felony. Police say he was taken to a juvenile detention center after his arrest but it is not known if he remains there.
Student attendance was down on Monday as several parents stated on social media they intended to keep their children home.
A book club event at the elementary school, scheduled for 9 a.m. Monday, was moved to Tuesday due to a lack of attendance.
At Du Quoin High School, a Du Quoin police squad car was positioned outside the building while students were in class.
"We just had a heightened tension to the school day," Vancil said on Monday. "We had officers assigned to the two public school buildings all day."
Police became aware of the reported threat at 10:30 a.m. Sunday morning. At 3:40 p.m. an email to parents and guardians was sent by Du Quoin Unit District 300 Superintendent Gary Kelly, Du Quoin High School Principal Matt Hickam and high school Assistant Principal Jeff Gossett.
"Our school and district takes any and all threats toward the safety and security of our schools very seriously," Kelly wrote. "The matter is being handled by law enforcement and the (Perry County) state's attorney's office.
He added that all Du Quoin schools would have a law enforcement presence on Monday, while students were to have classes on their normal schedule.
Similar emails went out to parents of Du Quoin elementary and middle school students.
State's Attorney David H. Searby Jr. said the nature of the case limits what information he can release. The exact contents of the social media post, and its connection to the district, have not been officially released.
"With it being a pending juvenile case, there's not much I can say," Searby Jr. said.
Vancil told the Du Quoin Call on Sunday that he was thankful the post was reported to police.
"I'm glad it came out this way instead of finding it out after the fact," Vancil said.
The Sandy Hook Elementary School shooting took place on Dec. 14, 2012, in Newton, Connecticut. Twenty-year-old Adam Lanza fatally shot 20 children and six staff members before taking his own life.
The Du Quoin Call will have more information as it develops.