Two flight attendants reported dizziness and four passengers fainted aboard an American Airlines flight Friday, forcing the pilot to drop the jet's oxygen masks and land in Ohio, an airline spokesman said.

All 132 people on Flight 547 from Reagan National in Washington, D.C., to Chicago's O'Hare Airport walked off the Boeing 737 after it landed at Dayton International Airport, but two passengers and a flight attendant were taken to hospitals, airline spokesman Ed Martelle said.

The two passengers were able to return to the airport and accompanied their fellow passengers on a replacement plane to Chicago. The flight attendant was admitted for overnight observation, airline spokesman Tim Smith said.

Christina Saull, a passenger from Washington, said there had been problems with the air conditioning and cabin-pressurization system before the plane took off, and maintenance personnel went into the cockpit of the plane on the ground in Washington, the Dayton Daily News reported.

After the flight took off, two women passed out and passengers started complaining about fumes or being lightheaded, Saull told the newspaper. Saull said she didn't smell anything, but a few minutes later, "they were announcing they were going to drop the masks."

Martelle said he wasn't able to confirm any of the details provided by the passenger, but he said the airline was investigating to determine the cause of the problems.

Dayton airport Director Terrence Slaybaugh said the pilot alerted the airport that some passengers were "complaining about the air and were experiencing some discomfort."