A U.S. official says the famine in Somalia has killed more than 29,000 children under the age of 5.

The United Nations has said that tens of thousands of people have died in the Horn of Africa's drought and famine, but the U.S. estimate is the first precise death toll offered in the crisis.

Nancy Lindborg, an official with the U.S. government aid arm, told a congressional committee in Washington on Wednesday that the U.S. estimates that more than 29,000 children under age 5 have died in the last 90 days in southern Somalia.

The U.N. on Wednesday declared three new regions in Somalia famine zones. Out of a population of roughly 7.5 million, the U.N. says 3.2 million Somalis are in need of immediate lifesaving assistance.