Deputy Chief Brian Simpson said officers were aware the three cousins had left the country, and police did all they could with that information when they learned it.
"We did have knowledge that those individuals were overseas," Simpson said Thursday. "Past that, I can't offer much.
"In the areas that are involved, to get information is hard. To get that information confirmed is even harder."
He said the three were known to police before they left and there was an indication that they may have been high-risk travellers.
Edmonton police informed the RCMP, which has the mandate to handle terrorist or extremist activities.
The CBC has quoted the father of one of the men, who said the three were radicalized in Edmonton and died fighting with the Islamic State of Iraq and the Levant.
Ahmed Hirsi told CBC his son Mahad, 20, died last fall along with cousins Hamsa and Hersi Kariye.
Simpson did not confirm the names.
Hirsi told the broadcaster that in 2010, Mahad moved from Toronto to Edmonton to live with his aunt. He began attending a local mosque and from there became radicalized, moving in with the two cousins.
The CBC quoted other family members disputing that the trio died fighting for ISIS, saying they had only gone to Egypt to further their religious education.
Simpson said there are other investigations going on into radicalized young people in the city and right across Canada.
"We've had two attacks in this country. We've seen what happened in France recently. We saw what's happened in Australia. So we have to be attuned to the issue," he said.
"We've got a great country here and it's a balance. You don't want to create paranoia.
"We want to create knowledge and education to allow people to have the tools and the ability to deal with this effectively."
Simpson also clarified remarks made this week to The National Post newspaper by Edmonton Police Chief Rod Knecht.
Knecht, in the interview was commenting on how Parliament Hill shooter Michael Zehaf Bibeau had worked in the oil industry, where workers can earn vast sums in short periods of time.
Knecht agreed in the article that it is possible other extremists may be working in Fort McMurray.
"The EPS is not saying that Fort McMurray is a hotbed for extremism or terrorism, or any other community in Alberta for that matter," said Simpson.
"However, the economics in Fort McMurray make it easier for these types of activities to be funded easily and quickly, as was the case with the Ottawa shooter."
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