Longtime NFL coach Tony Sparano dead at age 56

Tony Sparano was entering his third season as Minnesota Vikings offensive line coach.

Former Miami Dolphins head coach Tony Sparano, who spent nearly two decades in coaching positions for nine different NFL franchises, has died. He was 56.

The Minnesota Vikings announced Sunday that Sparano had "unexpectedly" passed away earlier that morning. Sparano was entering his third season as the Vikings' offensive line coach.

"Tony was a passionate and driven individual who cared deeply about his family, and especially enjoyed spending time with his grandchildren," team owners Mark and Zygi Wilf said in a a statement. " ... 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."

Vikings head coach Mike Zimmer said Sparano was "a great teacher, a grinder of a worker and had a toughness and fighting spirit that showed in our linemen ... This is just sinking in for us but Tony will be sorely missed by all."

A Connecticut native, Sparano began his NFL coaching career with the reborn Cleveland Browns in 1999. He became head coach of the Dolphins prior to the 2008 season and led the team to an 11-5 record and the AFC East title in his first season. After a pair of 7-9 seasons, Sparano was fired 13 games into the 2011 campaign, with the team sitting at 4-9.

Three years later, Sparano was named interim head coach of the Oakland Raiders after Dennis Allen was fired four games into the 2014 season. Under Sparano, the Raiders won just three of their final 12 games to finish the year with a 3-13.

Prior to arriving in Minnesota, Sparano spent the 2015 season as the tight ends coach for the San Francisco 49ers.

Sparano also held offensive coaching positions with the Washington Redskins, Jacksonville Jaguars and Dallas Cowboys.

Sparano played at the University of New Haven where he was a four-year letterman. He was hired as New Haven's head coach in 1994 and held that position for five seasons.

Sparano is survived by his wife, two sons, a daughter and four grandchildren.

The Vikings open training camp on July 28.

The Associated Press contributed to this report.