Retired NBA great Dennis Johnson, who won championships with the Celtics and Sonics and was currently coaching the D-League's Austin Toros, suddenly passed away at the age of 52.

Johnson reportedly (AP, ESPN) collapsed after practice and went into cardiac arrest, dying in Brackenridge hospital.

Below are some statements about Johnson released today:

David Stern, NBA Commissioner:

Whether he was leading his teams to NBA championships or teaching young men the meaning of professionalism, Dennis Johnson’s contributions to the game went far beyond the basketball court. Dennis was a man of extraordinary character with a tremendous passion for the game and his loss will be felt throughout the basketball community. On behalf of the entire NBA family, I extend my deepest sympathy to his wife Donna, his children Dwayne, Denise and Daniel, and their entire family.

David Kahn, Austin Toros owner:

“On behalf of Southwest Basketball and the Austin Toros family, we are deeply saddened by the passing of our head coach, Dennis Johnson. Dennis was a remarkable man and an excellent role model for our young players and front-office staff. He instantly commanded respect based on his past accomplishments in the NBA, but earned far more from us with his unpretentious demeanor, his dedication to the job, and his community service in Austin. He was a delight to be around, with a one-of-a-kind laugh that, like him, deserves a spot in the Hall of Fame. We share our sympathy with Donna and his children, and want them to know they will always be a part of the Toros family.”

Danny Ainge, Former teammate and current Celtics GM:

I was deeply saddened to learn about the sudden passing of Dennis Johnson. I had the great privilege of playing alongside DJ in the backcourt for six seasons and two championships. He was one of the most underrated players in the history of the game, in my opinion, and one of the greatest Celtic acquisitions of all time. DJ was a free spirit and a fun personality who loved to laugh and play the game. He was a good teammate and a good friend. We had spoken at length just the other night about basketball and his excitement about coaching the Austin Toros. DJ was in good spirits, so his passing comes as a shock. He will be sorely missed by the Celtics Family.

Kevin McHale, Former teammate and Timberwolves VP of Basketball Operations:

I'm shocked and saddened after hearing the news about D.J. He was truly one of the good guys to play in the NBA, and he was a great teammate who was fun to be around. My sympathies go out to his wife and kids. He was way too young to pass away.

Elgin Baylor, Vice President of Clippers Basketball Operations:

Speaking for our entire organization, I want to say how saddened we are to hear this shocking news. Dennis was a joy to be around and a terrific person. He will truly be missed by the many people whose lives he touched. Our deepest sympathies go out to his family.

Jeff Lenchiner, editor of InsideHoops.com:

Dennis Johnson, along with the other key 80's Celtics, played a tremendous role in making me fall in love with basketball in the first place. I loved the way they played. They got me hooked. DJ and his teammates are indirectly responsible for the very existence of Inside Hoops. And leaving his teammates behind and just focusing on Dennis, I've met and talked with him a number of time, and he was terrific. Great guy. Now he's gone. We've been robbed. DJ should have gotten another 30, 40, 50 years. His death is a sad reality check; a reminder that every day really is a gift. I wish all the best to his friends and family.

Lenny Wilkens, Seattle Sonics Vice Chairman:

Dennis was a great player for the Sonics. He helped us win a championship and was the MVP of the Finals. But more importantly, he was a tremendous person. He seemed to be enjoying coaching in Austin, and was in great spirits. He’s left us way too soon. Sometimes, recognition comes slowly, but Dennis will go down as one of the true leaders in Sonics history, and he was recently honored as a member of the Sonics’ 40th Anniversary Team. All of us at the Sonics and Storm family send our sympathies to his wife and children.