Minnesota Vikings offensive line coach Tony Sparano has died unexpectedly at the age of 56, the team announced Sunday afternoon.

"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."

Sparano had complained about chest pains and went to the hospital Thursday, a source told ESPN's Chris Mortensen. Sparano underwent tests and was released Friday. The source said Sparano's wife found him unconscious Sunday morning as they prepared to leave for church but could not revive him.

An assistant with Minnesota for the past two seasons, Sparano worked for nine NFL teams over 19 seasons, with head-coaching stints in Miami (2008-11) and on an interim basis with Oakland (2014). He held positions with Cleveland, Washington, Jacksonville, Dallas, San Francisco and the New York Jets.

Tony Sparano, who coached with nine NFL organizations in his career, had been the Vikings' offensive line coach since 2016. Nick Wosika/Icon Sportswire

Sparano was 32-41 as a head coach. In 2008, his first season at the helm in Miami, he took the Dolphins to his only playoff appearance. The Dolphins won the AFC East with an 11-5 record that season, the only time in the past 15 seasons that the division wasn't won by the New England Patriots. Sparano became the first coach in NFL history to take a team to the playoffs the year after a one-win season.

"Tony made an indelible impact on our team's history and his toughness, grit and leadership were evident to everyone who had the chance to coach with or play for him," Dolphins owner Stephen Ross said in a statement. "On behalf of the entire Dolphins organization, we extend our most heartfelt condolences to his wife Jeanette and the entire Sparano family."

Sparano's no-nonsense, gruff exterior was synonymous with the signature sunglasses he wore at all times. He wore the sunglasses, even in low lighting, because of a hot oil accident he sustained while working at a fast food restaurant at age 17 in his native Connecticut.

"You can see there's still a scar on my face," Sparano told the (Minneapolis) Star Tribune in 2016. "I had a patch over my left eye for 22 days, a patch over my right eye for 14. The left eye never did get right. The cornea is burnt and sun-sensitive, light-sensitive.

"I hear people always say, 'Why does he have these sunglasses on at a night game?' Or, 'Why is he wearing them inside?' Hey, it's that kind of bright light that causes my eyes to start running, tearing and crying."

Sparano had reunited with Vikings coach Mike Zimmer in Minnesota. The two coached under Bill Parcells with the Cowboys from 2003 to 2006.

"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," Zimmer said in a statement. "This is just sinking in for us but Tony will be sorely missed by all."

This offseason, Sparano was also reunited with new offensive coordinator John DeFilippo on the Vikings' staff. Sparano and DeFilippo coached together in Oakland in 2013 and 2014.

Sparano spoke with ESPN on the Vikings' final day of minicamp in June about how his previous relationship with DeFilippo and their mutual respect helped facilitate the seamless transition once the former Philadelphia Eagles quarterbacks coach took over offensive coordinator duties in February.

"I think Flip knows me enough to trust me in the things that I'm doing there," Sparano said. "You can get line coaches in this league that are afraid to change and afraid to do something different, and they're stuck in their ways one way or the other. I've sat in every seat, and Flip knows that; Flip and I have talked about that a bunch of times, you know where you've sat in every seat and for me whatever he wants to do, whatever he wants to try, I'm good with that.

"Plus the terminology portion of it was easy for me; we can go back and we can grab things that you know my line calls, Flip is familiar with. His terminology, I was familiar with. So now there's two people going at it in the room that way instead of just one person trying to coach the coaches. You know there's two of us going at it that way a little bit, and when it really comes down to it at the end of this whole thing, my position as a line coach and his position as a coordinator, those two have to work well together, and I think, you know, I was excited when he was the guy that we chose, and I kind of knew that this could be a good thing and he brings a lot of passion and energy, and that's the kind of football I like to play."

He was remembered on Twitter by several players, including Vikings tight end Kyle Rudolph, former Vikings and current Jets quarterback Teddy Bridgewater, Raiders quarterback Derek Carr and former Dolphins wide receiver Brian Hartline and offensive tackle Jake Long.

Thoughts and prayers to Mrs. Sparano, his family and everyone in the @Vikings organization.. life's precious and we just never know when it's our time.. RIP Coach.. https://t.co/vOzlSoUTlq — Kyle Rudolph (@KyleRudolph82) July 22, 2018

You will truly be missed by your loved ones, the guys you coached and the ones you've impacted over the years coach Sparano. Calm, cool and always wearing your shades no matter how dark the room was. Thank you for caring about the us as individuals and not just athletes 🙏🏾. — Teddy Bridgewater (@teddyb_h2o) July 22, 2018

Sporano Family I am so sorry for your loss. Coach believed in me, trusted me, and stuck with me as a rookie. He would check on my family every HC and QB meeting we would have! He was a great man! I love you coach! — Derek Carr (@derekcarrqb) July 22, 2018

Heart broken and lost for words! We lost a great man. Prayers to the Sparano family. So glad I got to see you and tell ya how much you meant to me a month ago. @Vikings #RIPTony — Brian Hartline (@brianhartline) July 22, 2018

The most memorable moment in Sparano's NFL coaching career came in Week 3 of the 2008 season, when the Dolphins surprised Patriots coach Bill Belichick with a single-wing-style Wildcat formation, beating New England 38-13. That loss is still the Patriots' largest home loss in the Belichick era (playoffs or regular season), and it snapped New England's 21-game regular-season win streak.

Six times the Dolphins ran plays from the formation at New England, snapping the ball directly to running back Ronnie Brown, and four of those plays resulted in touchdowns.

"It was like playing hide-and-go-seek, making them guess,'' Brown said at the time.

Sparano is survived by his wife, Jeanette; his two sons, Tony and Andrew; his daughter, Ryan Leigh; and four grandchildren.

Sparano was born Oct. 7, 1961, in West Haven, Connecticut. He played in college at the University of New Haven and was the head coach at the school from 1994 to 1998.

ESPN Stats & Information and The Associated Press contributed to this report.