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.”

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.

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

Anyone with information about the threat should call police.

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