Airport officials in Kansas City say a passenger jet struck a flock of birds shortly after takeoff and returned to land safely.

The Frontier Airlines flight took off about 7 p.m. Saturday night bound for Denver when it hit the birds at an altitude of about 4,000 feet.

Kansas City International Airport spokeswoman Kathleen Hefner told KSHB-TV that both engines were hit, but only one lost power.

Passengers said they saw flames shooting from one of the engines and there was a terrible smell in the cabin.

Bird-aircraft collisions are not unusual, but they are being more scrutinized since US Airways Flight 1549 safely ditched in the Hudson River in January after striking a flock of geese after takeoff from New York's LaGuardia Airport.