Officers initially responded to an assault call in the 7400 block of Hazeltine Avenue at 2:50 a.m. PT, according to the Los Angeles Police Department.
"There were several neighbors that had dialed 911 after hearing an argument," said LAPD Detective Mark O'Donnell.
Authorities said that arguing between a man and his mother ended after he pushed her out of her second-story bedroom window.
Police later identified the man as 41-year-old Fernando Vargas and the mother as 71-year-old Carlota Vargas.
Witnesses say Fernando Vargas immediately jumped out after pushing his mother and began kicking her while she was on the ground.
She was transported to an area hospital, where she was pronounced dead, police said.
Authorities said Fernando Vargas was in police custody and that he was taken to a hospital to be treated for a leg injury.
"I was really scared at the time it was happening, seeing all that. The woman coming out the window, and then him jumping out and stomping on her was horrible," said a neighbor who did not want to be identified.
Investigators said the incident was apparently the result of a domestic dispute. The nature of that dispute was unknown.
There were conflicting reports on whether Fernando Vargas lived with his wife along with his mother at the location, or if his wife had since moved out. Our sister station KABC says they do know that the Vargases have lived in the building for more than a decade.
Chopper video showed at least five police vehicles in front of an apartment building, whose three residential levels sit above a street-level parking garage.