Cape Breton Regional Police are investigating after someone set off a flare inside Memorial High School in Sydney Mines, N.S. on Thursday.
Staff and students evacuated the school shortly before 10:30 a.m. after a smoke alarm went off.
After searching the building, police and fire officials discovered a smoke signal canister underneath a stairwell.
Orange smoke was visible in the windows of the school.
Police say no one was injured in the incident.
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As a precaution, the Cape Breton-Victoria Regional School Board has closed Memorial High School for the remainder of the day.
The school board says buses will be returning students home immediately.
Police say the canister found at the high school appears to be similar to the one found inside North Sydney Walmart earlier this week.
READ MORE: Cape Breton police investigating after smoke canister set off inside Walmart
Police are investigating both incidents and asking anyone with information that can help identify the persons responsible for lighting the flares to contact police or Crime Stoppers.
With files from Cory McGraw