Dennis "Dee Tee" Thomas, a co-founder of the legendary soul-funk band Kool and the Gang, whose hits included "Celebration," died on Saturday at age 70, the group announced.

Thomas, "beloved husband, father and a co-founder of Kool & the Gang, passed away peacefully in his sleep at the age of 70 in New Jersey," said a Facebook statement from the group.

Another founding member, Ronald Bell, died last year.

"An original member of Kool & the Gang, Dennis was known as the quintessential cool cat in the group, loved for his hip clothes and hats, and his laid-back demeanor," his bandmates wrote.

"Alto saxophone player, flutist, percussionist as well as master of ceremonies at the band's shows," he made his farewell appearance with the group on July 4 at the Hollywood Bowl in Los Angeles, the statement added.

Kool and the Gang became a major smash in the 1970s, pumping out hits like "Get down on it," "Jungle Boogie" and "Ladies' Night," with its brassy funk putting it in a class with Earth, Wind and Fire, the Isley Brothers and Sly and the Family Stone.

Dennis Thomas, with white hat and saxaphone, performs with other members of Kool and the Gang during the Songwriters Hall of Fame 49th Annual Induction and Awards Dinner at New York Marriott Marquis Hotel on June 14, 2018 in New York City
Dennis Thomas, with white hat and saxaphone, performs with other members of Kool and the Gang during the Songwriters Hall of Fame 49th Annual Induction and Awards Dinner at New York Marriott Marquis Hotel on June 14, 2018 in New York City AFP / ANGELA WEISS

Brothers Robert and Ronald Bell, along with friends Thomas, Robert Mickens, Charles Smith, George Brown and Ricky Westfield founded the group in 1964 in New Jersey, first under the name the Jazziacs.

The long-running group fused jazz, soul and funk.

Thomas was the group's stylist, the statement said, making sure they "always looked fresh."

"In the band's early days, Dennis also served as the 'budget hawk,' carrying the group's earnings in a paper bag in the bell of his horn."

Kool and the Gang was inducted into the Songwriters Hall of Fame in 2018.

It remains a DJ favorite and is heavily sampled especially in the rap world, its tracks appearing in songs by artists including Jay-Z, Nas, NWA, Tupac, The Wu-Tang Clan, Snoop Dogg, A Tribe Called Quest and Busta Rhymes.