Some transborder flights with Canadian airlines were impacted Wednesday when the U.S. Federal Aviation Administration (FAA) temporarily grounded all domestic routes due to a major computer outage.

The number of affected Canadian airline flights wasn’t immediately known after routes resumed mid-morning. The FAA lifted the ground stop shortly before 9 a.m. EST as it probed the source of the issue, though service impacts continued to ripple through airports across the U.S.

Air Canada said in a statement that transborder operations would be affected by the outage “but it is not possible to determine the extent at this point as we do not know the full impact and duration.”

“We are putting in place a goodwill policy for affected customers to change their travel plans,” the airline said in an email.

WestJet said six flights were delayed due to the outage, though none had been cancelled as midday Wednesday. Porter Airlines said two flights were cancelled and passengers were rebooked, with “flights operating normally” by Wednesday afternoon.

Both Air Canada and WestJet advised customers to check the status of their flights before heading to the airport. The Greater Toronto Airports Authority, which operates Pearson International Airport, offered similar advice for travellers bound for the U.S., pointing to “some delays” for transborder flights.

More than 7,000 flights were delayed as of midday on Wednesday due to the outage and more than 1,000 were cancelled.

With files from the Associated Press.