The Montreal-Trudeau International Airport said Friday afternoon that all flights to and from the U.S. have been temporarily suspended. The notice comes as the Federal Aviation Administration in the U.S. issued a nationwide ground stop for all departing flights ”due to extraordinary circumstances and reasons for safety." The FAA said the ground stop is related to air traffic control communications issues. A notice on the Montreal airport’s website states that flights to and from the U.S. are suspended “until further notice.” “Passengers are encouraged to check their flight status directly with their airline,” the airport said, adding that flight delays and cancellations are expected. 40 flights cancelled, others might be affected Saturday Airport spokesperson Eric Forest told CTV News that 40 flights were cancelled on Friday. Those include 24 departures and 16 arrivals. No flights have been diverted to the YUL airport. Airport operations were gradually returning to normal late Friday evening but travellers are being warned that some flights might still be affected on Saturday. At around 8:20 p.m., the FAA lifted the nationwide ground stop that led to the cancellation of more than 4,000 flights across the U.S., according to FlightRadar24. However, some aviation analysts said it could take days for airlines to resume normal operations. Air Canada said all flights to and from the United States have been cancelled for the remainder of the evening. It also said flights between Canada, the Caribbean, and South America that travel through the U.S. “may also be impacted.” Trump administration officials blamed “overloaded” and “outdated” air traffic systems for the outage. NAV Canada, which operates civil air traffic in Canada, told CTV News that it is monitoring the situation and that its systems are operating normally. It also had to temporarily implement “traffic management measures” at the Montreal airport and others in order to safely manage traffic volumes. ‘Very frustrating’: Travellers stranded in Montreal The outage caused chaos across airports in Canada and the U.S. Upwards of 10,000 flights were delayed. Passengers at the Montreal airport were scrambling to find ways to get to their destination. “It’s very frustrating,” said one passenger who booked a cruise and was not sure whether he would be able to find another flight. “We don’t know what to do. Do we go home? Do we stay here? They have no news,” he told CTV News. Another man who was supposed to fly to Washington, D.C. was among the travellers who were stranded. “It’s a real inconvenience but that’s life,” he said, adding that he would likely head home in Montreal to watch some sports. With files from CTV News’ Anastasia Dextrene and The Associated Press