Former NBA all-star and longtime Boston Celtic guard Dennis Johnson died on Thursday after collapsing following a practice.

The 52-year-old was coach of Boston's NBA development league affiliate, the Austin Toros.

Dennis Johnson (3) died Thursday at the age of 52 in Austin, Texas. Dennis Johnson (3) died Thursday at the age of 52 in Austin, Texas.
(A. D. Bernstein/Getty Images)

Johnson was unconscious and in cardiac arrest when paramedics arrived at Austin Convention Center, said Warren Hassinger, spokesman for Austin-Travis County Emergency Medical Services.

Paramedics tried to resuscitate him for 23 minutes before he was taken to a hospital and pronounced dead, Hassinger added. Mayra Freeman, a spokeswoman for the medical examiner's office, said there will be an autopsy.

Known as "DJ," Johnson played on three championship teams with Seattle and Boston in a 13-year career that also included a stop in Phoenix.

"Dennis was a great player, one of the best teammates I ever had, and a wonderful person," said former Celtic teammate Larry Bird, now president of the Indiana Pacers. "My thoughts and condolences are with his family at this difficult time."

Considered one of the best defensive players in league history, Johnson was a five-time all-star who averaged 14 points and five assists per game.

He often saved his best for the playoffs, averaging 17 points and earning the postseason MVP award in 1979 when the Supersonics defeated Washington for the championship.

"I'm a winner," he once said. "I put my heart into the game. I hate to lose. I accept it when it comes, but I still hate it. That's the way I am."

After a three-year stint with the Suns, Johnson came to Boston in a 1983 trade that helped solidify a Celtic lineup that included Bird, Kevin McHale and Robert Parrish.

The team would win the NBA championship in 1984 and 1986, and make the finals on two other occasions. Johnson retired a Celtic in 1990.

Johnson later served as an NBA assistant and was promoted to interim coach of the Los Angeles Clippers in 2002, but was let go after the team went 8-16.

The Toros postponed home games scheduled for Friday and Saturday nights.

With files from the Associated Press