LAS VEGAS — Mary Wilson, one of the original members of the Supremes, the 1960s girl group that helped establish the Motown sound and propelled Diana Ross to superstardom, has died. She was 76.

Wilson died Monday night at her home in Las Vegas and the cause was not immediately clear, said publicist Jay Schwartz.

Wilson, Diana Ross and Florence Ballard made up the first successful configuration of The Supremes, Motown’s first and most commercially successful girl group. Ballard was replaced by Cindy Birdsong in 1967, and Wilson stayed with the group until it was officially disbanded in 1977.

The Supremes, with Diana Ross, lead singer on top of the slide, while Mary Wilson climbs the stairs and Florence Ballard stands underneath, in 1966. Wilson, the longest-reigning original Supreme, has died at 76 years old. AP Photo, file

The group’s first No. 1, million-selling song, “Where Did Our Love Go,” was released June 17, 1964. Touring at the time, Wilson said there was a moment when she realized they had a hit song.

“I remember that instead of going home on the bus, we flew,” she told The Associated Press in 2014. “That was our first plane ride. We flew home. We had really hit big.”

It would be the first of five consecutive No. 1s, with “Baby Love,” “Come See About Me,” “Stop! In the Name of Love” and “Back in My Arms Again” following in quick succession. The Supremes also recorded the hit songs “You Can’t Hurry Love,” “Up the Ladder to the Roof” and “Love Child.”

“I just woke up to this news,” Ross tweeted on Tuesday, offering her condolences to Wilson’s family. “I am reminded that each day is a gift,” she added, writing “I have so many wonderful memories of our time together.”

Motown founder Berry Gordy said he was “extremely shocked and saddened to hear of the passing of a major member of the Motown family, Mary Wilson of the Supremes.” His statement Monday night, according to Variety, said “The Supremes were always known as the ‘sweethearts of Motown.’”

Wilson, Ross and Ballard were inducted into the Rock and Roll Hall of Fame in 1988.

“The world has lost one of the brightest stars in our Motown family. Mary Wilson was an icon,” Motown Museum Chairwoman and CEO Robin Terry said in a statement.

Wilson, in a recent YouTube video posted Saturday, said she was excited to celebrate Black history month, her upcoming birthday (March 6) and teased fans with the announcement that Universal Music had plans to release some of her music.

“We’re going to be talking about the Supremes, yeah, 60th anniversary, and I’m going to be talking a lot about that mainly because I’ve finally decided how to work with Universal and they’re going to release new recordings, Mary Wilson recordings,” she said. “Yes! At last!”

“Hopefully some of that will be out on my birthday,” she continued. “We’ll see. I’ve got my fingers crossed here. Yes I do.”

Several celebrities mourned Wilson’s death on social media, including Questlove, Andy Cohen, Janet Mock, Ledisi, Richard Marx and Kiss’ Paul Stanley, who said he was in touch with Wilson last week.

“OMG! Mary Wilson of the Supremes has died suddenly. I was just on a Zoom call with her Wednesday for about an hour & never could have imagined this,” he tweeted Tuesday. “So full of life & great stories. Absolutely shocked. Rest In Supreme Peace Mary.”