School officials in three Canadian provinces and one territory all received similar bomb threats this week, but responses to the potential danger varied.
Universities and schools across Prince Edward Island were evacuated Wednesday morning after police received a fax from someone threatening to detonate bombs at several schools. Three colleges in Nova Scotia were also evacuated after receiving threats.
Hours later, a school board in Winnipeg received a similar bomb threat, but no schools were evacuated.
And on Thursday, schools in three regions of Nunavut were closed due to a bomb threat, but reopened after lunch.
'Can't examine a bomb threat in a vacuum'
"Assessing a bomb threat is very, very difficult," said Chris Mathers, a Toronto-based crime and risk consultant. "You can't examine a bomb threat in a vacuum."
Mathers said a number of factors are considered when assessing the credibility of a bomb threat, including the frequency of the threats and whether similar threats have been made.
"If you're getting a bomb threat every day, eventually someone had to make a decision not to act out as the person making the threats wants them to," said Mathers. "And typically, serious bombers don't call it in."
But he said with minimal information available, many officials would err on the side of caution, as was the case in P.E.I.
P.E.I. schools evacuated
P.E.I. RCMP Staff Sgt. Kevin Baillie said when the threat was received Wednesday, police didn't have enough information to determine whether the threat was credible or not.
"There's no question — the vast majority of these types of threats are not credible. However, in the early stages, it's very difficult to say definitively that the threat is not credible," said Baillie, adding that the decision to evacuate schools was made by the school board.
"It's a very difficult decision to make and I think in the vast majority of cases, it's prudent to err on the side of caution. But no matter what way you go, you're opening yourself up to criticism."
Winnipeg police monitored Maritime threats
Police in Winnipeg said they were monitoring the threats in P.E.I. and Nova Scotia when a school board there received a similar threat.
"If the person is making this threat in P.E.I. and Halifax, the likelihood of one individual carrying out the threat as it was described in multiple locations across a country was effectively impossible," said Winnipeg Police Service spokesman Const. Rob Carver.
But officials have the difficult task of balancing the safety of the people being targeted by the threat with creating unnecessary panic, said Carver.
"We don't want to be reacting to one of these a week where we're emptying schools out and somebody thinks this is a joke," said Carver.
"But our officers always assume we're making life and death decisions. We don't take this lightly. But we also don't take lightly putting a city on panic."
Thursday Nunavut threat
As for the threat in Nunavut on Thursday, RCMP Sgt. David Lawson said officials did consider the similar threats in P.E.I, Nova Scotia and Winnipeg, but decided to physically check schools as a precaution.
"We just wanted to ensure all the students were safe," said Lawson.