A suspicious package investigation shut down parts of Seattle-Tacoma International Airport for more than three hours Sunday evening, causing departing passengers to miss flights.

Port of Seattle officials say untagged, unattended luggage in the Alaska Airlines ticketing area led to the investigation.

Officials say there was never a direct threat, but out of “an abundance of caution” port police shut down the ticketing areas on the north side of the airport and the upper departures drive.

The bomb squad came in and, after rendering the package safe with a loud blast, eventually discovered the bag contained scuba and fishing gear.

The shutdown had cascading effects on air travelers, many of whom were stuck in traffic jams approaching the airport with all vehicles squeezing into the lower arrivals drive.

Without access to their ticket counters, agents for Alaska Airlines, SEA’s largest tenant, set up makeshift check-in areas at the south end of the terminal.

Check-in lines were long, as were TSA security lines because the northern checkpoints were closed.

With so many travelers squeezed into the southern screening lines, wait times exceeded 75 minutes.

Alaska Airlines officials said an air traffic control ground stop delayed about a dozen of their flights.