Director Rob Reiner and wife Michele Singer stabbed to death in their LA home, sources say

"This is a devastating loss for our city and our country," Mayor Bass said.

Director Rob Reiner and his wife, Michele Singer, were found dead in their Brentwood home, according to a statement from their family.

"This is a devastating loss for our city and our country," Mayor Karen Bass said in a statement. "Rob Reiner's contributions reverberate throughout American culture and society, and he has improved countless lives through his creative work and advocacy fighting for social and economic justice."

Firefighters responded at 3:38 p.m. to a medical aid call at a home in the 250 block of Chadbourne Avenue, according to the Los Angeles Fire Department. The deceased were initially identified only as a man and woman ages 78 and 68 years old, the LAFD said.

Police launched a death investigation that later developed into a murder case, LAPD sources told ABC News, adding that property records show the house belongs to Reiner.

The LAPD's Robbery-Homicide Division is leading the investigation, and the department's senior leadership responded to the scene. 

According to a neighbor, actors Billy Crystal and Larry David arrived separately at the home on Sunday evening. The two comedians stayed briefly before departing, and Crystal "looked like he was about to cry," the neighbor said.

There are two houses that the Reiner family owns across the street from each other. Rob and his wife lived in one and a daughter with kids lived in another, according to the neighbor.

The son of comedy legend Carl Reiner and singer Estelle Lebost, Rob Reiner is known for massive Hollywood hits, including "The Princess Bride," "When Harry Met Sally...," "Stand By Me," "This is Spinal Tap" and many more.

Rob Reiner first became famous on the Norman Lear television sitcom "All in the Family."

"The Lear Family is devastated by the deaths of Rob and Michele Reiner," the family said in a statement on Sunday night. "Norman often referred to Rob as a son, and their close relationship was extraordinary, to us and the world."

"Lyn Lear had remained very close with them and said, 'The world is unmistakably darker tonight, and we are left bereft,'" the statement added.

California Gov. Gavin Newsom addressed Reiner's death, saying he is "heartbroken by the tragic loss."