The incident unfolded just after 3 a.m. Monday at the dispensary on Pico Boulevard, according to the Los Angeles Police Department.
The suspect, who was wearing a ski mask, drove his car into the business, according to Det. Samuel Marullo. The security guard on duty believed a robbery was occurring and shot the suspect once.
He was able to run away from the scene, but was found shortly after on the sidewalk near Centinela Avenue. He was rushed to the hospital but did not survive.
The victim has only been described as a 25-year-old man.
The security guard who opened fire was not arrested. An investigation into the shooting is ongoing.