Flags at the King Center were lowered to half-staff Tuesday morning.

"We appreciate the prayers and condolences from people across the country," the King family said in a statement. The family said she died during the night. The widow of the Rev. Martin Luther King Jr. suffered a serious stroke and heart attack last August.

"It's a bleak morning for me and for many people and yet it's a great morning because we have a chance to look at her and see what she did and who she was," poet Maya Angelou said on ABC's "Good Morning America."

"It's bleak because I can't many of us can't hear her sweet voice but it's great because she did live, and she was ours. I mean African-Americans and white Americans and Asians, Spanish-speaking she belonged to us and that's a great thing."

King died at Santa Monica Hospital, a holistic health center in Rosarito Beach, Mexico, 16 miles south of San Diego, said her sister, Edythe Scott Bagley of Cheyney, Pa.

She had gone to California to rest and be with family, according to Former Atlanta Mayor Andrew Young, who broke the news on NBC's "Today" show.

At a news conference, Young said Coretta King's fortitude rivaled that of her husband.

"She was strong if not stronger than he was," Young said. "She lived a graceful and beautiful life, and in spite of all of the difficulties, she managed a graceful and beautiful passing."

She was a supportive lieutenant to her husband during the most tumultuous days of the American civil rights movement, and after his assassination in Memphis, Tenn., on April 4, 1968, she kept his dream alive while also raising their four children.

"I'm more determined than ever that my husband's dream will become a reality," King said soon after his slaying.

She goaded and pulled for more than a decade to have her husband's birthday observed as a national holiday, first celebrated in 1986.

King became a symbol, in her own right, of her husband's struggle for peace and brotherhood, presiding with a quiet, steady, stoic presence over seminars and conferences on global issues.

The Rev. Jesse Jackson, who was with her husband when he was assassinated, said Tuesday that she understood that every time he left home, there was the chance he might not come back. "Like all great champions, she learned to function with pain and keep serving," he said. "So her legacy is secure as a freedom fighter, but her work remains unfinished."

King wrote a book, "My Life With Martin Luther King Jr.," and, in 1969 founded the multimillion-dollar Martin Luther King Jr. Center for Nonviolent Social Change. She saw to it that the center became deeply involved with the issues she said breed violence hunger, unemployment, voting rights and racism.

"The center enables us to go out and struggle against the evils in our society," she often said.

She became increasingly outspoken against businesses such as film and television companies, video arcades, gun manufacturers and toy makers she accused of promoting violence. She called for regulation of their advertising.

After her stroke, King missed the annual King holiday celebration in Atlanta two weeks ago, but she did appear with her children at an awards dinner a couple of days earlier, smiling from her wheelchair but not speaking. The crowd gave her a standing ovation.

At the same time, the King Center's board of directors was considering selling the site to the National Park Service to let the family focus less on grounds maintenance and more on King's message. Two of the four children were strongly against such a move.

Also in the news recently was a new book, "At Canaan's Edge" by Taylor Branch, that put allegations of her husband's infidelity back in the spotlight. It said her husband confessed a long-standing affair to her not long before he was assassinated.

Coretta Scott was studying voice at the New England Conservatory of Music and planning on a singing career when a friend introduced her to Martin Luther King, a young Baptist minister studying at Boston University.

"She said she wanted me to meet a very promising young minister from Atlanta," King once said, adding with a laugh: "I wasn't interested in meeting a young minister at that time."

She recalled that on their first date he told her: "You know, you have everything I ever wanted in a woman. We ought to get married someday." Eighteen months later June 18, 1953 they did, at her parents' home in Marion, Ala.

The couple moved to Montgomery, Ala., where he became pastor of the Dexter Avenue Baptist Church and organized the famed Montgomery bus boycott in 1955. With that campaign, King began enacting his philosophy of direct social action.

Over the years, King was with her husband in his finest hours. She was at his side as he received the Nobel Peace Prize in 1964. She marched beside him from Selma, Ala., into Montgomery in 1965 for the triumphal climax to his drive for a voting rights law.

Only days after his death, she flew to Memphis with three of her children to lead thousands marching in honor of her slain husband and to plead for his cause.

"I think you rise to the occasion in a crisis," she once said. "I think the Lord gives you strength when you need it. God was using us and now he's using me, too."

The King family, especially King and her father-in-law, Martin Luther King Sr., were highly visible in 1976 when former Georgia Gov. Jimmy Carter ran for president. When an integration dispute at Carter's Plains church created a furor, King campaigned at Carter's side the next day.

She later was named by Carter to serve as part of the U.S. delegation to the United Nations, where Young was the ambassador.

In 1997, she spoke out in favor of a push to grant a trial for James Earl Ray, who pleaded guilty to killing her husband and then recanted.

"Even if no new light is shed on the facts concerning my husband's assassination, at least we and the nation can have the satisfaction of knowing that justice has run its course in this tragedy," she told a judge.

The trial never took place; Ray died in 1998.