The was a larger police presence  Wednesday around Peninsula Shores District School in Wiarton.

Police were cautious after graffiti was written on a trailer at the back of the school property.

Parents also erred on the side of caution as about half of the 600 pupils at the school were not in class Wednesday.

The graffiti contains the numbers 666 with a drawing of a devil's head and the phrase: "When the lights go out on November 13, the innocent will die."

Principal Dave Waddington says officials believe it's another case of vandalism but they have taken the incident seriously.

A letter was sent home to parents, explaining the incident, and giving them the option of keeping kids home.

He says the incident likely happened on the weekend after Halloween, but there is no video footage of suspects on the school's security cameras.

Waddington believes the incident is linked to a posting on the Internet about a power outage simulation in the U.S.

“It has some significance because there’s a simulated power grid test in the U.S. and there’s online discussion that the lights will go off and won’t come back on and then a whole bunch of negative stuff.”

But he says they have confirmed the outage will not affect Ontario.

Student Nick Kreutzwiser was at school.

“Nothing like this ever happened at Wiarton before so I think a lot of people are looking at what’s happened in the States and in the past and getting scared.

"I don’t think there’s much of a threat. I mean, look, we’ve got three cop cars in the parking lot. We’re pretty safe,” he says.