Jake and Romy Reiner, the children of renowned Hollywood director Rob Reiner and wife Michele Singer Reiner, are speaking out for the first time after their brother, Nick Reiner, was arrested for allegedly killing their parents.

“Words cannot even begin to describe the unimaginable pain we are experiencing every moment of the day,” Jake and Romy Reiner said in a statement released by a family spokesperson on Wednesday. “The horrific and devastating loss of our parents, Rob and Michele Reiner, is something that no one should ever experience. They weren’t just our parents; they were our best friends.”

“We are grateful for the outpouring of condolences, kindness, and support we have received not only from family and friends but people from all walks of life,” Jake and Romy Reiner said. “We now ask for respect and privacy, for speculation to be tempered with compassion and humanity, and for our parents to be remembered for the incredible lives they lived and the love they gave.”

Nick Reiner, 32, is charged with two counts of first-degree murder, with the special circumstance of multiple murders, for allegedly stabbing his parents to death on Sunday, according to prosecutors.

The Reiners’ daughter is the one who found her parents’ bodies in their Brentwood home on Sunday, sources told ABC News.

Rob Reiner and Michele Singer Reiner, who met while Rob Reiner was directing “When Harry Met Sally…,” married in 1989 and share three children: Jake, Nick and Romy. Rob Reiner is also survived by daughter Tracy Reiner with his first wife, Penny Marshall.

ABC News’ Brooke Stangeland contributed to this report.