"It is with very heavy hearts that all of us within the Senators family remember Mark who was truly a wonderful father, husband, player, coach and friend," Senators owner Eugene Melnyk is quoted saying in a media release issued Tuesday.
"Mark's charismatic fighting spirit was present right until the end. We are all better for having had the opportunity to work so closely with Mark whose passion for life, hockey and his family will leave an indelible mark on our organization. The entire Ottawa Senators organization sends its deepest condolences to the Reeds family."
Reeds coached the Owen Sound Attack of the OHL for four years before being called up to help coach the Sens in 2011.
He is survived by his wife, Mary, and their two children, Kyle and Kelsey.
Originally from Toronto, Reeds was recognized with the Matt Leyden Trophy as the 2010-11 OHL coach of the year, according to his biography on the Ottawa Senators website.
He led Owen Sound to the OHL playoffs in two of his four seasons, while his team posted a 119-118-35 record in 272 regular season games.
Reeds was drafted to the NHL by the St. Louis Blues in 1979, and played in 365 games while registering 159 points with the Blues and Hartford Whalers between 1981 and 1989.