An American Airlines (search) plane made an emergency landing Thursday at O'Hare International Airport (search) after experiencing engine problems shortly after takeoff. Authorities said the plane landed safely and there were no injuries among the more than 100 people aboard.

Black marks could be seen on the side of a left engine as the plane sat on a runway about half an hour after it landed Thursday afternoon, and passengers were being let off through a front exit and onto the tarmac.

The plane was American Airlines Flight 1374 to Philadelphia with 107 passengers on board, airline spokeswoman Mary Frances Fagan said.

Fagan said there was a fire in the engine and the engine was damaged, but the cause had not immediately been determined, though it may have involved birds getting into the engine.

"We believe it was probably a bird strike," Fagan said. She said that belief was based on pieces missing from the engine.

As the plane was still in the air, several people on the ground called saying they heard an explosion overhead and saw flames shooting from the engine of the airplane, according to Chicago Fire Department officials.

There were also reports of falling debris, and authorities in nearby Niles were looking at a piece of metal that had been reported as falling onto an empty softball field.

Chicago Fire spokesman Dennis Gault said no injuries or damage were immediately reported on the ground.

The problem with the plane was reported about 2:14 p.m. CDT, said Chicago Department of Aviation spokeswoman Annette Martinez. She said there were no injuries.