The FBI has been called in to investigate a plane crash at San Francisco airport.

Two Chinese teenagers died when the Asiana Airlines Boeing 777 from Seoul, burst into flames yesterday as it landed.

Mechanical failure has been ruled out by the Korean airline involved.

The black box has been recovered and it will now be analysed in Washington as they try to work out exactly what happened.

Investigators say the plane, which crash landed at San Francisco airport, was going too slow during it's approach.

One of the investigators, Deborah Hersman, explained that the aircraft's controls vibrated - warning the pilots just before the crash.