Students returned to class Monday morning at an orthodox Jewish boys school in Montreal, two days after a firebomb attack early Saturday damaged the facility.

The incident, which was caught on security camera and has brought an anonymous donation of $5,000 in reward money, has left the school's president trying to decide what to do next.

"Our only concern is the safety of the children," said Fred Gestetner, who has considered bringing in counsellors for the children and is looking at increasing security.

"We are shocked with it, but it's something we have to handle in this day and age, I guess."

The incident at the Taldos Yakov Yosef school in Outremont has not been declared a hate crime by local police because of the absence of graffiti or other evidence. The damage was minimal, but local Jewish groups say they are sure it's anti-Semitism.

"The best possible conclusion is that people understand these kind of acts are unacceptable and should never take place in a free and democratic society," said Steve Slimovitch, of B'nai Brith. "But that seems to be not the case."

This was the second incident in two years involving a firebomb attack on a local Jewish school.

In 2004, the library at Montreal's United Talmud Torah school was destroyed by fire. A note left at the scene said it was in retaliation for the Israeli army's killing of a Hamas leader in the Middle East.

A 19-year-old man was sentenced to two years in prison in 2005 for the attack.