Several airports across Canada were forced to respond to bomb threats on Thursday, triggering evacuations, flight delays, and security sweeps that affected hundreds of passengers.

The RCMP confirms that airports in at least five provinces received threats during the day, including facilities in Vancouver, Calgary, Edmonton, Winnipeg, Ottawa, and Montreal.

In each case, the airports worked with local police and emergency crews to secure the areas and investigate.

Nav Canada says in the interest of security protocols, they can’t disclose the specific nature of the threat but will continue to work closely with investigators.

No devices or suspicious items were found during sweeps of the affected airports, and while some flights were affected, schedules were back to normal relatively quickly and remain running normally on Friday.