Deicer fumes billowing into the cabin of a grounded plane sent fire engines and ambulances racing to Seattle's Sea-Tac Airport Wednesday.
The problem developed as Alaska Airlines Flight 528 was preparing to take off for Burbank, California, with 143 passengers and a crew of five.
Alaska Airlines spokeswoman Caroline Boren said officials had not determined how the fumes entered the plane.
About 20 people were treated for eye irritation, said an airport spokesman, Perry Cooper. He said one crew member and two passengers were taken to a hospital but their conditions did not appear to be serious.
Boren says there have been no other deicer problems during a week of snow in the Seattle area.
The incident occurred around 8:20 a.m. Wednesday, FOX KCPQ reported.
Alec Mashek, a passenger on a neighboring plane, told KCPQ he could see at least 10 fire trucks and half a dozen ambulances, some of which were leaving the tarmac with their sirens blaring.
The Associated Press contributed to this report.