Travelers in Seattle are being asked to complete as much of the preflight process as possible at home after a cyberattack left the Seattle-Tacoma International Airport without internet and web systems.

The Port of Seattle, which includes the airport, published a statement on Saturday afternoon warning that hours earlier it “experienced certain system outages indicating a possible cyberattack.”

“The Port isolated critical systems and is in the process of working to restore full service and do not have an estimated time for return,” port officials said. The port’s website was still down as of Monday morning.

“We are working closely with appropriate authorities and partners to help travelers who may be impacted. If you are traveling today, please check with our airline partners for travel information and allow extra time to get to SEA and to your gate.”

They urged flyers to handle mobile boarding passes and checked bags through airline apps before they arrive at the airport. Extra time will be needed to navigate the airport and terminal screens are still having issues showing up-to-date flight information.

The Seattle Times reported that some airlines have been forced to manually sort more than 8,000 bags and hand write boarding passes. 

The Port of Seattle did not respond to requests for an update on the situation. Saturday’s statement said there was no estimated time for when systems will return to normal. 

The airport is the busiest in the Pacific Northwest region, serving more than 50 million passengers in 2023. The Port of Seattle — a government agency that owns parks, container terminals and more — has a budget of $670 million and about 2,000 employees.

Cybersecurity protections around ports and airports have been a key focus of government agencies as the number of damaging attacks has increased. 

TSA issued emergency regulations in 2023 for airports and aircraft operators that require them to have pre-approved implementation plans for increased security measures.

There have been dozens of cyberattacks and ransomware incidents targeting ports and airports over the last three years. Ports across Belgium, the Netherlands, Germany, Portugal, Japan, Australia and in U.S. cities like Houston have all faced attack. 

President Joe Biden issued an executive order in February giving the US Coast Guard more authority to respond to cyber incidents after Department of Homeland Security Secretary Alejandro Mayorkas warned that cyberattacks were one of the most urgent threats facing ports.

Seattle is still recovering from a ransomware attack in May that took down the city’s library system. There have also been ransomware attacks on a major cancer center in the city and several other government agencies.