LAPD said officers responded around 3:45 p.m. to a home in the 3700 block of Oak Hill Avenue after they received a radio call about a person who claimed he shot his grandmother.
LAPD Officer Mike Lopez said police tried to talk to the suspect, who then allegedly made threats he would shoot any officer who entered the home.
A SWAT team was later called and entered the residence after an hours-long barricade. A man and woman were found dead, Lopez said.
Police believe the man fatally shot his grandmother and then shot himself.
A firearm was recovered, Lopez said. Ballistics investigators will look into whether the same gun was used in both shootings.
The names of the man and woman were not immediately released, but the suspect was believed to be in his 30s and the woman in her 60s.
LAPD is still investigating a motive.