Defenceman Steve Montador, who played 571 NHL regular-season games and had a role in the Calgary Flames reaching the 2004 Stanley Cup final, has died. He was 35.

The Vancouver native was found unconscious in his home in Mississauga, Ont., early Sunday morning and was later pronounced dead, according to Peel Region Police.

While no cause of death was known, the police said no foul play was suspected.

"The NHL family was saddened to learn of the passing of Steve Montador," commissioner Gary Bettman said in a statement released to to the media. "Steve's career was defined by a passion for the game and a determination that made him a great teammate as well as a respected opponent. We extend our deepest sympathies to Steve's family and friends."

Montador, who was plagued by concussions through his hockey career, suffered a concussion in March 2012 and a year later talked openly and candidly about the injury and subsequent depression.

“It is with deep sorrow that we mourn the passing of Steve Montador," the Flames said through a released statement. "Steve will always be remembered to us as a member of the Flames family. We are very proud that he wore the Calgary uniform over six seasons and also of his important contributions during that period both on and off the ice.

"We would like to express our sincere condolences to the Montador family. This is a terrible loss of a wonderful young man; a great teammate known for his big heart and character. He will be missed by all who had the pleasure to have known and worked with him.” 

Montador told CSNChicago.com in 2013 of the anxiety and depression that accompanies a concussion, saying he received a lot of help to work through his issues and believed he had take the appropriate steps in his recovery.

In March 2013, Montador reported feeling better and said: "Just every day is a brand new day and there's a lot of enjoyment. … I'm just filled with a lot of gratitude."

Montador signed a contract with Medvescak Zagreb in Russia's Kontinental Hockey League later that year and never played again in the NHL. He last played in the league for Chicago in the 2011-12 season, scoring five goals and 14 points in 52 games.

The Blackhawks on Sunday released a statement on Montador's passing.

"With deep sadness we mourn the unfortunate loss of former Blackhawk Steve Montador. We join the many others throughout the NHL in keeping Steve's family and friends in our thoughts and prayers during this difficult time.”

"To my friend Steve Montador may u find peace in a better place," former Blackhawks teammate Nick Boynton wrote on Twitter. "I'll miss you."​

In 10 NHL seasons, Montador compiled 33 goals and 98 assists for 131 points and 807 penalty minutes.

One of Montador's memorable games occurred in June 2004 when he scored the winning goal at 18:43 of overtime to beat San Jose in Game 1 of the Western Conference final.

Montador played for the Ontario Hockey League's North Bay Centennials, Erie Otters and Peterborough Petes. He began his NHL career with the Flames during the 2001-02 season.

He was traded to Florida on Dec. 2, 2005 and spent three seasons with the Panthers, raising his point total from nine in the 2006-07 season to 23 the following campaign.

Montador left Florida as a free agent and signed with Anaheim, playing less than a full season for the Ducks before he was traded to Boston on March 4, 2009.

A free agent that summer, Montador joined the Buffalo Sabres for two seasons, recording a career-high 26 points in 2010-11 before a trade to Chicago.

"We are all deeply saddened to learn of the sudden death of Steve Montador," Don Fehr, executive director for the NHLPA, said in a released statement. "Steve was a great person who quickly became a friend of everyone he came to know in the game; teammates, NHL club staff, the media and fans.

"Over the course of his career, he was an active member of the NHLPA and someone who I and our entire staff, enjoyed working closely with. He dedicated a lot of his time to advancing the interests of his fellow players. On behalf of the players and staff, we send our thoughts and prayers to Steve's family and his many friends. He will be greatly missed."

In a November 13, 2011 game for the Blackhawks, Montador saved a goal for his team, skated down the ice and made a nice move, beating Edmonton Oilers goalie Nikolai Khabibulin.

With files from The Canadian Press