LOS ANGELES (Reuters) - Hollywood composer James Horner, who scored the Oscar-winning film "Titanic" and its mega-hit theme song "My Heart Will Go On", died in a plane crash in southern California on Monday, U.S. media reported.

The aircraft came down in the Los Padres National Forest, north of Los Angeles, triggering a fire that charred more than an acre of brush, local fire authorities said.

Star actors from Russell Crowe to Kirstie Alley took to Twitter to pay tribute to Horner, after trade publications The Hollywood Reporter and Variety reported he had died in his private plane.

Director Ron Howard wrote: "Brilliant Composer James Horner, friend & collaborator on 7 movies has tragically died in a plane crash. My heart aches for his loved ones."

Horner, 61, won two Academy Awards for his work on "Titanic", one for the score and one shared with lyricist Will Jennings for best original song - "My Heart Will Go On", performed by Celine Dion.

Horner also composed the music for "Aliens", "The Karate Kid", "Braveheart" and a string of other major films. His scores for "Avatar", "A Beautiful Mind" and "House of Sand and Fog" earned Oscar nominations.

His attorney Jay Cooper told Reuters he had not heard from Horner since the crash, but could not confirm whether he was on board at the time. "He's an experienced pilot, but I know nothing else," Cooper said.

The Ventura County Fire Department said the plane crashed at 9:30 a.m. (1230 EDT Sunday) and there were no survivors. The cause of the crash was not immediately known.

(Reporting by Steve Gorman in Los Angeles and Curtis Skinner in San Francisco; Editing by Andrew Heavens)