Steve Montador last played in the NHL with the Blackhawks during the 2011-12 season. He suffered a concussion in February 2012 and played in just one game the rest of the season.
Former NHL player Steve Montador died early Sunday morning at age 35.
Peel Region Police, who received an emergency call at approximately 2 a.m., say Montador was found unconscious in his home in Mississauga, Ontario, and was later pronounced dead.
No foul play or suicide was suspected, according to police. The cause of death was not immediately known.
"There is an autopsy being conducted, but that is because of his age," Peel Region Police constable Fiona Thivierge told ESPN. "It not is considered to be suspicious in nature.
"His family has been contacted. They are devastated. They have asked for privacy."
NHL commissioner Gary Bettman said Montador, a 10-year NHL veteran, had a "passion for the game."
"The NHL family was saddened to learn of the passing of Steve Montador," Bettman said in a statement. "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 last played in the NHL for the Chicago Blackhawks during the 2011-12 season and played overseas in the European Kontinental Hockey League for the Zegreb Medvescak last season. He suffered a concussion in February 2012 and played in just one game the rest of the year.
"With deep sadness we mourn the unfortunate loss of former Blackhawk Steve Montador," the Blackhawks said in a statement released Sunday. "We join the many others throughout the NHL in keeping Steve's family and friends in our thoughts and prayers during this difficult time."
Blackhawks coach Joel Quenneville and forward Patrick Kane both called Montador a great friend and teammate.
"Tough when you get that news right before the game," Quenneville said. "You know, teammate, good friends, a guy who was here not too long ago that was a teammate. It's always sad when you hear something like that."
"It's sad, been a sad year, a couple guys passing away that are young guys," Kane said. "It seems kind of surreal. Very, very sad news.
"He was a happy guy, always around the room making jokes, very sociable, wanted to be part of the team and wanted to make friendships. I'll always remember him as a good, nice guy."
Montador made his NHL debut in 2001 with the Calgary Flames and played for six teams in parts of 10 seasons. The defenseman had 33 goals and 98 assists in 571 career games.
"He was a wonderful man with a huge heart," Montador's agent, Kurt Overhardt, said to ESPN.com. "This is a sad day."
NHL Players Association executive director Don Fehr issued a statement later Sunday, calling Montador "a great person."
"We are all deeply saddened to learn of the sudden death of Steve Montador," Fehr said in the 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."