Tony Sparano, whose NFL coaching career included a 2014 stint as interim head coach of the Raiders, died unexpectedly Sunday.

Sparano was 56. The cause of death has not been disclosed.

According to Chris Mortenson of ESPN, Sparano and his wife, Jeanette, were about to leave for church when she found him unconscious in their kitchen. She tried CPR, but he could not be revived.

Mortenson reported that Sparano had gone to a hospital Thursday, complaining of chest pains. Tests were performed and he was released Friday, Mortenson said.

Sparano coached for nine NFL teams in a career that began in 1999 as a Cleveland Browns assistant. He was currently the offensive line coach for the Minnesota Vikings.

In 2013, Sparano was hired by the Raiders as offensive line coach and assistant head coach under Dennis Allen. When the Raiders started 0-4 in 2014, Sparano took over as head coach. The Raiders went 3-9 under him.

The Vikings, Raiders and 49ers expressed their condolences via social media about Sporano’s passing.

The Raiders’ website reads,

“The Raiders family was deeply saddened to learn of Tony Sparano’s passing this morning. Tony had a deep passion for football and was embraced by the Raider Nation during his time with the Silver and Black. Tony will be sadly missed by the entire NFL community. Our hearts are with Jeanette and the Sparano family during this difficult time.”