(CNN) A firefighter is being called a "hero" for trying to rescue two boys trapped inside a car that plunged into the Port of Los Angeles.

Police don't know why the car veered off Berth 73 at the Port of Los Angeles on Thursday, but when emergency crews arrived, two adults were swimming on the surface. The car was submerged in about 30 feet of water. The two boys were trapped inside.

Rescue crews tried to save them, but unfortunately one child pulled from the car, a 13-year-old boy, died at a local hospital. Another 8-year-old boy is reported in "grave condition." The adults -- believed to be the boys' parents - were pulled from the water in fair condition.

Almost 100 Los Angeles Fire Department personnel and divers were involved in the rescue operation -- including four LAFD fireboats.

Los Angeles City Councilman Joe Buscaino singled out one firefighter as a hero.

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