The Pegula family issued a statement Tuesday saying, "Kim is receiving medical care as a result of some unexpected health issues. We are very grateful for the progress she has made over the past few days. She has an exceptional team of medical experts at her side. We ask that you keep Kim and our family in your prayers and ask that you respect our need for privacy."
Pegula, 53, is president and CEO of Pegula Sports and Entertainment. She oversees the business operations of the Bills and Sabres and is the first woman president of both an NFL and NHL team.
Kim and Terry Pegula, 71, purchased the Bills in 2014 after becoming owners of the Sabres in 2011.
Quarterback Josh Allen said that the players learned Tuesday that Kim Pegula is dealing with health issues and that it came as a surprise to the team.
"We're all praying for them, and we appreciate everyone in the community praying for them as well," Allen said. "She's done so much for our organization, and we all love her so much. Again, as a team we're saying our prayers, and we just ask that you guys do the same for us, please."
Kim Pegula has been a public advocate for increasing diversity in the NFL and NHL, and she sits on the NFL's workplace diversity committee. Pegula also serves on the NFL's Super Bowl and major events advisory committee, business ventures committee and NFL foundation committee.
Born in Seoul, South Korea, Pegula was adopted at 5 years old by a Canadian family based in Fairport, New York, east of Rochester. She later attended Houghton College, living all her early life in western New York.
The Pegulas also own the National Lacrosse League Buffalo Bandits and Rochester Knighthawks and the AHL's Rochester Americans. An agreement was reached this year on a new $1.4 billion stadium that will keep the Bills in Orchard Park, New York, for the foreseeable future with a 30-year lease.
Alongside commissioner Roger Goodell, the Pegulas visited the site of the racist shooting that killed 10 people in an East Buffalo supermarket last month.
The Pegulas have five children: Jessica, Kelly, Matthew, Michael and Laura.
The family did not provide any further details about Kim Pegula's condition.
Bills coach Sean McDermott, who was hired by the Pegulas in 2017 and has led the team to three straight winning seasons and consecutive division titles, said Tuesday, "What [Kim and Terry Pegula] have done for me, for my family, for this team and this city and western New York -- just being there for them, all of us collectively offering our prayers and support and giving them the privacy that they need, is important during this time."