"Our hearts go out to Jeanette and the entire Sparano family as we all mourn the loss of Tony," Vikings owners Mark and Zygi Wilf said in a statement. "Tony was a passionate and driven individual who cared deeply about his family, and especially enjoyed spending time with his grandchildren. Tony's presence within the Vikings organization will be deeply missed. We are only thinking of Tony's family during this incredibly difficult time. We ask that the entire NFL and Vikings family keep the Sparanos in their thoughts."
Sparano was entering his third season as the Vikings' offensive line coach under head coach Mike Zimmer. It was the latest stop in a two-decade long NFL coaching career that began in 1999 when he was hired as an offensive quality control coach for the new Cleveland Browns franchise.
After several assistant coaching jobs with multiple NFL teams, the Dolphins hired Sparano as their head coach in 2008 following the team's 1-15 campaign. He guided the Dolphins to an 11-5 mark and a first-place finish in the AFC East in 2008, becoming the first coach in NFL history to lead a team to the postseason after a one-win season.
Sparano posted a 29-32 record in his nearly four seasons with the Dolphins.
He served as the Oakland Raiders' interim head coach in 2014 after the team fired Dennis Allen, posting a 3-9 mark.
"I am at a loss for words with Tony's sudden passing," Vikings general manager Rick Spielman said in a statement. "Tony loved the game of football and his players. More importantly, he was a strong man of faith who treasured his family. My heart is with the Sparanos today. As an organization we will support them in whatever ways we can."
The Hennepin (Minn.) County Medical Examiner announced Monday that the cause of death was "arteriosclerotic heart disease."
Zimmer offered his condolences over the loss of Sparano.
"I love Tony Sparano. He was a great teacher, a grinder of a worker and had a toughness and fighting spirit that showed in our linemen. He was a great husband, father and grandfather and a great friend to me. This is just sinking in for us but Tony will be sorely missed by all."
Sparano was born in West Haven, Connecticut, on Oct. 7, 1961. He was a starting center for the University of New Haven, where he played from 1978-81 and helped the NCAA Division II team achieve its first undefeated season in 1979. He is a member of the New Haven Football Hall of Fame.
After breaking into the collegiate coaching ranks with his alma mater as an offensive line coach from 1984-87, Sparano spent six seasons at Boston University, where he served as an O-line coach before being promoted to offensive coordinator. He then returned to New Haven in 1994 as the team's head coach, posting a 41-14 record over five seasons before joining the Browns' coaching staff.
Under Sparano's tutelage, the Vikings' offensive line established itself as one of the NFL's top units in 2017 -- especially in the run game -- after struggling in 2016. It also provided Case Keenum with the protection he needed to put together a breakout campaign that propelled Minnesota to the NFC Championship Game.
During the offseason, Sparano was reunited with new Vikings offensive coordinator John DeFilippo, who worked with him on the Raiders in 2013-14. Sparano was looking forward to their renewed collaboration. The Vikings will hold a team meeting Monday morning, sources informed of the situation told NFL Network's Tom Pelissero.
In addition to the Browns, Dolphins, Raiders and Vikings, Sparano coached with the Redskins, Jaguars, Cowboys, Jets and 49ers during his career. Many of his current and former players expressed their condolences on social media Sunday.
Sparano is survived by his wife Jeanette; his sons Tony and Andrew; his daughter, Ryan Leigh; and his four grandchildren.