A violent threat scribbled on the washroom wall of an Oakville, Ont. school is being taken seriously by police as they try to find out who left the message.

Halton Region Police responded to Iroquois Ridge High School Tuesday afternoon after a student found a message that said two gunmen would open fire there on Friday.

As word of the message went around the school, students were shocked by what it said.

"It is pretty scary to think that someone in our school even just wrote that as a joke," one student told CTV's Galit Solomon Wednesday. "But it could be real and that's even more scary."

Classes were in session on Wednesday and are expected to continue on Thursday. But the school board is trying to decide if the school will open on Friday."

Police do not believe there is any real danger to students, but they are not taking any chances with the threat.

"It's disturbing to me, both as a police officer and a parent," Staff Sgt. Gavin Hayes said Wednesday.

"I would be concerned of a threat if that was received where my kids go to school. But you have to put it into context. The author has placed everybody in a situation that you have to take it seriously," he added.

The situation has familiar overtones for police. Last summer one person was killed and several others wounded when a gunman opened fire inside Montreal's Dawson College. A similar high school shooting spree in 1999 claimed several lives at Columbine High School in the U.S.

School board sent a letter to parents about the threat. The letter explained what has happened and how board officials plan to proceed. It also noted that a specific time for Friday's shooting was not indicated in the washroom wall note.

Board officials have not decided if the school will be shut down on Friday.

With a report from CTV's Galit Solomon