8:51 AM PT -- Country superstar Alan Jackson -- who's known George for years -- tells TMZ ... “Well, heaven better get ready for some great country music."
He adds, "While George was known for his wild and crazy days, I’ve known him for 25 years as a friend. He had grown into a real good man. Of course, he will always be the greatest singer and interpreter of real country music – there’ll never be another."
"Like the song says, ‘You know this old world is full of singers, but just a few are chosen to tear your heart out when they sing. Imagine life without them…Who’s gonna fill their shoes.’”
8:04 AM PT -- George's publicist has released a statement on the singer's passing ... saying, "Today is a sad day for music. George said to me once, 'One day I'll Join the Angel band.' Well, today he did."
The statement continues, "George passed with his family by his side and the official cause of death is being listed as 'Hypoxic Respiratory Failure.'" FYI -- H.R.F. means the lungs couldn't pump enough oxygen to the rest of the body.
7:44 AM PT -- A family member tells TMZ ... "He has been on oxygen for a long while now and his lungs finally just couldn’t do it anymore and they collapsed and he passed away. He couldn’t breathe anymore on his own."
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