Departing flights at Ottawa Macdonald-Cartier and Montreal-Trudeau international airports were briefly halted on Thursday after bomb threats triggered ground stops, the U.S. Federal Aviation Administration said. The interruptions began shortly after 8 a.m. local time and were lifted later in the morning, although travellers were advised to expect lingering delays. Air-traffic manager NAV Canada said the threats targeted its facilities in six cities—Ottawa, Montreal, Edmonton, Winnipeg, Calgary and Vancouver—prompting evacuations of some staff and a temporary suspension of operations. The agency is working with police and other authorities to identify the source of the threats and restore normal schedules. The Ottawa Police Service confirmed it is leading an investigation at the capital’s airport. No injuries were reported and officials have not disclosed any suspects or motives. Airlines urged passengers to check flight status before heading to any of the affected airports.