ST. LOUIS (AP) -- A flight out of Lambert Airport in St. Louis made an emergency landing shortly after taking off for Los Angeles after the pilot reported a mechanical problem.

The American Airline MD-80 returned to Lambert shortly after taking off around 7:30 p.m. Sunday evening.

KMOV reports that an American Airlines representative said the plane was back on the ground by 8 p.m. Passengers were taken to another airplane and took off at 9:15 p.m.

The original plane was holding 137 passengers and six crew members.

The cause of the mechanical problem is still being investigated.