At Chicago O'Hare, American Airlines 767 catches fire on runway.

The right-side engine of an American Airlines Boeing 767 failed Friday during an attempted takeoff, sending debris as far as a half mile and passengers hurriedly down emergency slides onto a runway at Chicago's O'Hare International Airport.

Three sources familiar with the unfolding investigation told CNN the General Electric engine suffered an apparent "uncontained" failure.

The 161 terrified passengers and nine crew members scrambled to safety Friday afternoon after huge flames erupted on the right side of the plane.

Airport fire Chief Timothy Sampey said crews responded to a report of a No. 2 engine on fire. The plane, which had stopped well before the end of the runway, had about 43,000 pounds of fuel.

"This could have been absolutely devastating if it happened later," he said.

About 20 people were taken to the hospital with minor injuries that occurred during the evacuation down the emergency slides, District Chief Juan Hernandez said. There were people with minor bruising or injured ankles, he said. None of the injuries were caused by the fire.