Tony Gwynn, who won eight National League titles and had two World Series stints during his 20-year career with the San Diego Padres, has died of cancer on Monday at the age of 54.

According to reports, Gwynn, who is popularly known as "Mr. Padre," passed away on Monday morning at the Pomerado Hospital in California. His son, Tony Jr., who currently plays for the Philadelphia Phillies, confirmed the news through his Twitter account.

"Today I lost my Dad, my best friend and my mentor," Tony Jr. said. "I'm gonna miss u so much pops. I'm gonna do everything in my power to continue to make u proud."

Gwynn, who is a career .338 batter with 3,141 hits, was a 15-time All-Star and had five 200-hit seasons during his illustrious career with the Padres.

The baseball icon, who was a popular figure in San Diego after showing loyalty to the Padres by turning down lucrative offers from other teams, was inducted to the Pro Baseball Hall of Fame in 2007 -- three years after the Padres retired his No. 19 jersey.

"Tony will be remembered in baseball circles for his hitting acumen, as evidenced by a lofty .338 lifetime batting average and an astonishing eight National League batting titles," National Baseball Hall of Fame and Museum President Jeff Idelson said via ESPN. "But it was his infectious laugh, ever-present smile and humble disposition that made Mr. Padre a favorite in San Diego and an endearing figure to a nation of baseball fans who marveled at his career accolades and celebrated his 2007 induction into the Hall of Fame in record numbers."

MLB commissioner Bud Selig also issued a statement wherein he called Gwynn as the greatest Padre and one of the best hitters in league history.

"Major League Baseball today mourns the tragic loss of Tony Gwynn," Selig said in a statement. "The greatest Padre ever and one of the most accomplished hitters that our game has ever known, whose all-around excellence on the field was surpassed by his exuberant personality and genial disposition in life."

Gwynn worked as baseball coach of San Diego State, his alma mater, since 2002 before taking a medical leave in late March after undergoing intense cancer treatment.

The Hall of Famer underwent operations for cancer in his right cheek in August 2010 and February 2012. The second operation was reportedly a complicated procedure as the doctors were forced to remove facial nerve that intertwined with tumor inside Gwynn's right cheek.