Nick Carter and Aaron Carter's dad Robert Gene Carter, known as Bob, passed away suddenly at age 65 Tuesday.
"I am heartbroken to share the news that our father, Robert, passed away last night..." Nick wrote. "While we learn more about the cause of death, and begin the grieving process, we ask that our privacy be respected at this difficult time."
"My heart is Completly shattered I'm in shock and I loved my dad so much. #RIP DADDY I Love You," Aaron tweeted.
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He also shared a couple of throwback photos with him and Robert.
"My heart is broken," he wrote on Instagram. "We are so hurt we lost you poppa way too soon. You were never human to me, you were always my real life super hero #BobCarter #RIP #MyDaddy."
In addition to Nick, Robert is survived by wife Ginger Elrod and their son Kaden, Nick's mother and ex-wife Jane, Aaron's twin Angel Carter and daughter Bobbie Jean, 35, and another daughter, Virginia, from a previous relationship.