It was an unexpected day off for students at St. Peter's Catholic Secondary School in Barrie today.

They had to leave in a hurry when a fire broke out in the school. The damage to the school was too bad to let the students back in today, and the school will remain closed tomorrow as well.

This isn’t the first time Barrie's fire department has been called to a fire at the catholic high school. And today, there are many unanswered questions about what happened and who did it.

The evacuation came just after 9 a.m. this morning. More than 1,100 students and staff were forced out after someone started a fire in a boys’ bathroom on the top floor.

“We were in class and like we could smell the smoke,” says student Nico Ganhao. “And no one really knew what was going on. So we just kind of opened our door and saw the smoke from the bathroom coming out.”

Students say a teacher pulled the fire alarm. Within minutes the entire school was evacuated. Fire investigators say someone lit a plastic toilet paper holder and roll on fire. Damage is estimated at $10,000.

“Anytime there's plastics involved in a fire the toxicity is very, very high. And it produces a lot of black, dark, hot smoke,” says Samantha Hoffman with the Barrie Fire Department. “Which is what has travelled throughout the bathroom and out into the hallway.”

School staff tell CTV News there are no video cameras inside the building. But fire investigators are confident they will find who lit the fire.

“Somebody in that school knows who did this. And that's what we want. We want that information,” Hoffman says.

A catholic school board superintendent says air quality experts have been brought in to carry out a number of air quality tests. And the school’s principal says crews have been working on the bathroom all day.

“We are working on cleaning it all up. We are hoping that things will be back to normal,” says Heinrich Bebie.

Late this afternoon, CTV News learned the school will not open for class tomorrow. The cleanup isn’t finished and officials say it will remain off limits to everyone until it is safe to re-open.