SAN JOSE, Calif. - Three flight attendants fell ill on an Alaska Airlines flight from Seattle to San Jose Thursday from an unknown substance, NBC Bay Area reports.

One of the attendants was taken to the hospital, and the other two were treated and released at the airport.

During Flight 322, two attendants had not felt well. Before descending into San Jose, the flight attendants were in the front galley when they noticed a white powdery substance, according to an Alaska statement.

Michael Schreiber, a passenger on the flight, tweeted that the captain announced about an hour into the flight a "mysterious white powder was leaking from the plane's air vents," and suspected it was the result of deicing fluid getting sucked into the ventilation system and powderizing en route.

The flight landed about 6:45 p.m. at Mineta San Jose International Airport, and emergency crews and a hazmat team responded on the tarmac.

Crews believe the powdery residue is non-toxic and left over from deicing the plane. Alaska tweeted that "Deice fluid may have been ingested," in response to Schreiber's complaint.

No passengers were affected. They were held on the plane for about 45 minutes while crews assessed the situation.

There were not any impacts to the airport’s operation.