MLB umpire Eric Cooper has died, having officiated in the American League Division Series.
The league announced Cooper's death on Sunday, aged 52.
No cause of death had been revealed after Cooper officiated the ALDS series between the New York Yankees and Minnesota Twins just two weeks ago.
"This is a very sad day across Major League Baseball," MLB commissioner Robert Manfred said in a statement. "Eric Cooper was a highly respected umpire, a hard worker on the field and a popular member of our staff.
"He also served as a key voice of the MLB Umpires Association on important issues in our game. Eric was a consistent presence in the Postseason throughout his career, including in this year’s Division Series between the Yankees and the Twins. He was known for his professionalism and his enthusiasm, including for our international events.
"On behalf of Major League Baseball, I extend my deepest condolences to Eric's family, friends and all of his fellow Major League Umpires. We will honour Eric's memory during the World Series. Eric will be missed by the entire Baseball family."
Cooper started his officiating career in 1990 in the minors and had 21 years of MLB experience.
He was on the field for some of the biggest moments in recent baseball history, including being the home plate umpire for Hideo Nomo's no-hitter in 2001 and Mark Buehrle's no-hitter in 2007. He also was on the field for Buehrle's perfect game in 2009.
Cooper's assignments for officiating three no-hitters is the most among active MLB staff.
He also officiated the 2005 All-Star Game, the 2014 World Series and the 2009 and 2013 World Baseball Classic. Cooper also worked three wild-card games, 10 division series and four league championship series.