Three Dog Night co-founder and vocalist Cory Wells died Tuesday, according to the band's website. He was 74.

"It is with deep sadness and disbelief that I must report the passing of Cory Wells, my beloved band mate for over 45 years," Three Dog Night's Danny Hutton wrote in a press release. "Cory was an incredible singer – a great performer, he could sing anything."

Wells "died unexpectedly" in Dunkirk, N.Y. He had been touring with the band until September 2015 when he developed "severe back pain." No cause of death was given.

"Cory was like a brother in so many ways," said Hutton. "We had been together since 1965 and I am in shock at this sudden loss."

The group is best known for its 1960s and 1970s hits "Joy to the World," ''Mama Told Me (Not to Come)" and "Black and White." 

The band's keyboardist, Jimmy Greenspoon, died of cancer at 67 in March 2015. Wells said of his bandmate at the time, "I will be forever shattered by his death. Jimmy cared so much about excellence in the music and always made sure we had what we needed on stage and in the recording studio. I was amazed by his photographic memory, his love for music."

Wells is survived by his wife of 50 years, two daughters and five grandchildren.

The Associated Press contributed to this report.