CNN
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As the upcoming Labor Day holiday weekend is expected to send a record number of travelers to the skies, a cyberattack is forcing one of the nation’s largest airports to go back to basics. Computer systems at Seattle-Tacoma International Airport went down Saturday, and officials say they still don’t have an estimate for when they will be restored.

“We’re working around the clock to get necessary systems back online and to mitigate impacts for passengers,” aviation managing director Lance Lyttle said in a news conference Sunday.

The attack was focused on the Port of Seattle, which operates the airport. Online communications were affected, including the website used by the airport to advise passengers of their flight’s status, although there was a workaround web page with basic information up and running Wednesday. Airport Wi-Fi and the baggage processing system are down and the port’s email system went offline, officials said.

Port of Seattle officials have not revealed any details about how the cyberattack was carried out, except to say that “nefarious characters” were involved. “That is the question that is on everybody’s mind, and all of our staff are working to figure out what exactly occurred,” airport spokesperson Perry Cooper said in a Monday news conference.

The computer system outage comes as the TSA said it’s prepared to screen a potentially record-setting 17 million people over the holiday travel period and weeks after the global airline industry was hobbled by a CrowdStrike software issue that led to massive flight delays and cancelations.

While most major carriers at the airport process passengers using their own computer networks, which were unaffected, airport officials say smaller airlines and some international flights were impacted, forcing passengers to be checked in by hand. “Be prepared for long queues as some airlines are providing manual bag tags and boarding passes,” the airport advised in a post on X.

The airport known to many travelers as Sea-Tac – though it officially dropped that nickname in 2020 – enlisted a small army of Port of Seattle workers from other departments to don bright green vests and work in the terminal this week, advising people where to go and what to expect. Electronic screens, whose information is fed by the airport’s computer network, were replaced by white dry-erase boards.

Airport officials have emphasized their central aviation and security operations are not affected by the computer outage, with few cancellations and scattered flight delays reported. But it’s still a headache for fliers in the bustling airport – the nation’s eleventh busiest – who are being advised to check in online before arriving.

“It’s crazy with all of the signs being down from the cyberattack and all of the crew that are out here having to manually do things that normally would be done electronically,” a passenger told CNN affiliate KING Monday.

The cyberattack affected the airport’s automatic baggage processing, resulting in delays in some luggage arriving at the right destination, airport officials advised. “If you can travel without checking bags, do so,” Cooper said.

The Port of Seattle says federal investigators, including the FBI and the Department of Homeland Security, are looking into what happened. But as far as when the full website will be back up and the departure signs can light back up, airport officials remain in the dark.

“We do not have a time or a date as to when this will get resolved,” Cooper said Tuesday.