It happened at about 3 a.m. in the 8200 block of W. Sunset Boulevard, near Roxbury Road.
The Los Angeles Police Department says that the suspect was committing a robbery when the victim yelled at him to stop.
That's when the suspect shot the victim, a man in his 30s, and then took off, according to investigators.
The victim was taken to the hospital in grave condition.
A description of the shooter was not available.
No further details were immediately known. The investigation is ongoing.