President Obama condemned fatal shootings in Canada on Wednesday as "outrageous attacks." "We're all shaken by it," he said. 

Obama said the motive for the shootings remained unknown. But he said as more becomes known, that information will be factored into U.S. security considerations. "We have to remain vigilant," he said. 

Obama spoke by telephone Wednesday with Canadian Prime Minister Stephen Harper. Obama said he offered condolences on behalf of the American people. 

A Canadian soldier standing guard at a war memorial in the capital of Ottawa, Ontario, was shot and killed Wednesday. Gunfire also erupted inside Parliament nearby, and authorities say at least one gunman was killed. 

Obama spoke after holding a meeting with members of his Ebola response team in the Oval Office. 

On Monday, authorities said a recent convert to Islam killed one Canadian soldier before being shot to death by police. 

Obama also expressed the American people's solidarity with Canada.