A deputy has been fatally shot in a gun battle with America's most wanted man, ex-policeman Christopher Dorner, news.com.au reported.

The news site reported Dorner, 33, a former Los Angeles police officer and naval reservist, barricaded himself in a cabin at Big Bear, California.

Two law enforcement officers who were shot at by Dorner from the cabin were airlifted to hospita.

One of the deputies has died, Fox News reported.

San Bernandino police officers have urged Dorner to hand himself in.