Tracy Reiner In ‘Shock’ Over Deaths of Her Father Rob and His Wife

Hollywood and fans are reeling over the killing of Rob Reiner and his wife Michele … and the family is speechless, finding it difficult to comprehend the news.

TMZ broke the story … the legendary actor-director and his wife were slain in their Brentwood home Sunday … and we’ve learned the couple’s son Nick was in law enforcement custody as of Monday morning, being questioned about their deaths.

Tracy Reiner — Rob’s adopted daughter from his marriage to ex-wife Penny Marshall — told NBC News she had just seen her father the day before for a family gathering.

The actress — best known for her role in “A League of Their Own” — told the outlet … “I came from the greatest family ever. I don’t know what to say. I’m in shock.”

The deceased couple was discovered inside the L.A.-area home by one of their daughters … and she told police a family member had killed them.

Our sources also say the daughter told police the family member “should be a suspect” because they’re “dangerous.”

TMZ broke the story … Rob and Michele suffered lacerations consistent with knife wounds, and LAPD’s Robbery Homicide Division is investigating the case.

Rob was 78. Michele was 68.