OMAHA, Neb. (AP) -- A private funeral restricted to family will be held for Susan Buffett, the wife of billionaire investor Warren Buffett, one of her sons said Friday.

A time and place is not likely to be announced, Peter Buffett said.

"My dad really wants it private," Buffett said.

However, a public memorial service probably will be held, details of which have yet to be announced, Buffett said.

"It's a phenomenal loss," Buffett said. "There's also a need for thousands of people to somehow be part of a celebration of her life."

Susan Buffett died Thursday of a stroke at age 72 while she and her husband were visiting investor Herbert Allen of New York at his ranch in Cody, Wyo.

She spent a lot of her time on philanthropic work with organizations dealing with civil rights, reproductive health and AIDS awareness.

Peter Buffett said he flew to Cody and was at his mother's side when she died at the local hospital, as were his father and his sister, Susie.

The Buffetts' other son, Howard, could not make it to Cody because he was returning from a trip to Africa.

"It was clear, which is why we got there immediately, that it was something she wasn't going to recover from," Peter Buffett said.

His mother's death was a shock and did not appear to be related to her recovery from mouth cancer last fall, Buffett said.

"What brought it on, nobody knows," Buffett said of the stroke, declining to go into further detail of how his mother died.

Peter Buffett said he flew back to Omaha later Thursday to perform in his multimedia musical production based on American Indian themes, "Spirit: The Seventh Fire." The show is debuting in Omaha before going on to Milwaukee and Washington, D.C.

"The show is everything my mother represents, which is life and celebration and music," Buffett said. "It's only appropriate I be here."

AP-WS-07-30-04 1339EDT