SAN DIEGO -- John Butler, the San Diego Chargers' general manager and an architect of Buffalo's Super Bowl teams of the 1990s, died Friday of complications from lung cancer. He was 56.

Butler, diagnosed with the disease in July, was the Bills' general manager for eight seasons before taking that job in San Diego in 2001.

John Butler was in the middle of rebuilding the Chargers into winners. (AP)

"We lost a giant here, both literally and figuratively," Schottenheimer said.

Butler was a big man, an ex-Marine who could be both gruff and lighthearted.

"He gave you that bulldog impression, but he was always very helpful," said John Beake, an NFL vice president. "He was a straight-shooter and he had a big heart. He loved the game."

Butler had been hospitalized for four weeks. Schottenheimer said he spent time with Butler on Tuesday and Wednesday,

"We were talking about personnel, about the draft. Mentally, he was absolutely on top of everything. I did not sense any anxieties at all. He was very much at peace."

Butler was in Buffalo's front office for all of its record four straight trips to the Super Bowl from 1991-94. The Bills lost all of those NFL title games.

"All of our thoughts and prayers right now are with his wife, Alice, and daughter, Andrea," team president Dean Spanos said. "He meant so much to everyone here. It's hard to put into words this feeling of loss. We'll miss him."

Butler was considered one of the NFL's top talent evaluators.

As personnel director in Buffalo, he was known for finding big talent at small colleges, such as wide receiver Don Beebe of Chadron State and defensive end Phil Hansen of North Dakota.

A native of Chicago, Butler spent four years in the Marines and saw active duty in Vietnam. After his discharge, he enrolled at San Bernardino Junior College, then went to the University of Illinois, where he played one season on the offensive line before a knee injury cut short his playing career.

He coached for three seasons (1979-81) at the University of Evansville, then worked for George Allen and Marv Levy with the Chicago Blitz of the USFL. Butler served in a variety of capacities with the Blitz, including director of college scouting for three years while also coaching the tight ends and offensive line.

His first NFL job was as a scout for the Chargers in 1985.

He joined the Bills in 1987 as the personnel director, then became the team's general manager in 1993. During his tenure there, the Bills went to the playoffs 10 times and had a record of 140-83.

With the Chargers, he built the foundation for an offense by drafting quarterback Drew Brees and running back LaDainian Tomlinson. San Diego went 5-11 and 8-8 in Butler's two seasons.