was on lockdown Tuesday morning after an unknown caller threatened to bring weapons to school and start shooting.
According to police and Central Principal Steve Provis, students are not in danger.
"Everybody is absolutely safe," Provis said outside the school.
At least eight sheriff's deputy cars surrounded the high school after responding at 11:20 a.m. to an anonymous call that came through the Will County 911 dispatch.
Several deputies stood outside the school with guns. The school was on lockdown for about 40 minutes, and in that time no one was allowed in or out of the building.
By noon, the school was allowing students in and out of the building again. Police searched the entire school and are maintaining a presence throughout the day, sheriff's department spokeswoman Kathy Hoffmeyer said.
District spokeswoman Stacy Holland said officers will be at the entrances of all four Lincoln-Way high schools for the rest of the day. She wasn't sure whether any more precautionary measures would be taken the rest of the week.
As of 3:30 p.m., police were still investigating the origin of the anonymous phone call, sheriff's department spokesman Ken Kaupas said. He said he hopes to know by Wednesday afternoon whether police will be able to track the number. Kaupas added that no guns were found in the school.
Holland said all Central students were inside the building during the lockdown and that classes proceeded as scheduled.
Lincoln-Way posted a news release to its website shortly after 1 p.m. that said officers "assessed the situation and determined there was no immediate threat to students in school."
"We do appreciate the immediate response of the Will County Sheriff's Department and New Lenox Police Department," Supt. Larry Wyllie said in the release.
Stay tuned to Patch for more details as the story develops.
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This article has been updated to reflect that the anonymous call went to the 911 dispatch, not the school.