Irena Sendler, a Polish social worker who organized the rescue of some 2,500 Jewish children from the Nazis and was later honored by Israel's Yad Vashem memorial, has died.

Sendler's daughter, Janina Zgrzembska, told The Associated Press her mother died at a Warsaw hospital Monday morning. She was 98.

Sendler had lived at a Warsaw nursing home run by the Catholic Brothers of St. John of God since 2003, but had been in the hospital since last month with pneumonia.

Sendler was born Irena Krzyzanowska in Warsaw on Feb. 15, 1910. As a social worker with Warsaw's welfare department, Sendler masterminded risky rescue operations of Jewish children from the Warsaw Ghetto during Nazi Germany's brutal World War II occupation.

Records show Sendler's team of some 20 people saved almost 2,500 children from the Warsaw Ghetto between October 1940 and April 1943, when the Nazis burned the ghetto, shooting the residents or sending them to death camps.

Under the pretext of inspecting the ghetto's sanitary conditions during a typhoid outbreak, Sendler and her assistants entered in search of children who could be smuggled out and be given a chance to survive by living as Catholics.

Babies and small children were smuggled out in ambulances and in trams, sometimes wrapped up as packages. Teenagers escaped by joining teams of workers forced to labor outside the ghetto. They were placed in families, orphanages, hospitals or convents.

In hopes of one day uniting the children with their families — most of whom perished in the Nazis' death camps — Sendler wrote the children's real names on slips of paper that she kept at home.

When German police came to arrest her in 1943, an assistant managed to hide the slips — which Sendler later buried in a jar under an apple tree in an associate's yard. Some 2,500 names were recorded.

"It took a true miracle to save a Jewish child," Elzbieta Ficowska, who was saved by Sendler's team as a baby in 1942, recalled in an interview with The Associated Press in 2007. "Mrs. Sendler saved not only us, but also our children and grandchildren and the generations to come."

After World War II, Sendler worked as a social welfare official and director of vocational schools, continuing to assist some of the children she rescued.

In 1965, Sendler became one of the first so-called Righteous Gentiles that the Yad Vashem Holocaust memorial in Jerusalem honored for wartime heroics. Poland's communist leaders at that time would not allow her to travel to Israel, and she collected the award only in 1983.

Despite the Yad Vashem honor, Sendler largely remained forgotten in her homeland. Only in her final years, confined to a nursing home, did she finally become one of Poland's most respected figures, with President Lech Kaczynski and other politicians backing a campaign that put her name forward for the Nobel Peace Prize.

Sendler is survived by her daughter and a granddaughter.