Alan O'Day, the singer-songwriter best known for the No. 1 hit "Undercover Angel," died on Friday, May 17, after a battle with cancer, his label announced. He was 72.

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"Alan was a generous man who gave his heart and soul to the music industry," a statement from 1st Phase Records read, noting that he had continued to write and perform "until his last days." When he passed, at his home in Westwood, Calif., he was surrounded by family and friends. 

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O'Day first gained fame as a songwriter in the early 1970s, penning hits including Cher's "Train of Thought," the Righteous Brothers' "Rock and Roll Heaven," and Helen Reddy's "Angel Baby." He also co-wrote dozens of tunes for the Muppet Babies cartoons. In 1977, he rose to the top of the charts with his own single, "Undercover Angel."

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Grammy-winning songwriter Diane Warren mourned O'Day's loss on Twitter, using his own lyrics to give voice to her grief. "If there's a Rock n Roll Heaven, well U know they got one hell of a band," she wrote. "The band just got better, my friend. RIP."

O'Day is survived by his wife, Yuka.

This article originally appeared on Alan O'Day Dead: "Undercover Angel" Singer Dies at 72