CHICAGO (CBS) — Students at a west suburban high school will be met with bomb-sniffing dogs and a heavy police presence on Friday, after a possible bomb threat was found written on a bathroom wall.

The message was spotted Thursday afternoon on a stall in a girls’ bathroom at Elmwood Park High School. It said “Tomorrow school will blow, Feb. 19, 10 a.m.”

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Police said the threat is minimal, but they’re not taking any chances.

All after-school activities on Thursday were canceled, and on Friday all students must enter through the gymnasium, so police and bomb-sniffing dogs can check everyone who comes into the building. All bags will be checked as students enter the building.

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Police also were sweeping the entire campus before classes on Friday.

Anyone with information about the threat should call police.

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If the student who wrote the message is identified, he or she will face disciplinary action from the school, as well as criminal charges.