Three young girls whose disappearances set off a nationwide Amber Alert after their mother was found slain at their home were found safe today, authorities said.

SAGINAW, Mich. — Three young girls whose disappearances set off a nationwide Amber Alert after their mother was found slain at their home were found safe today, authorities said.

A tip from a motorist who heard the alert led Michigan state police to a car where the girls and their father were riding around noon, authorities said.

"The children are all safe and well," said Saginaw police Lt. Tammy Luty. She said the father was in custody had not been charged with any crime; he can be held for at least two days without charges being filed.

Saginaw police found the body of Erica Olguin, 32, at her Saginaw home Monday after she failed to pick up her 11-year-old son at school. Authorities said today they hadn't determined the cause of her death but that it was a homicide.

Police then issued the Amber Alert for her daughters, Victoria, 3; Lilliana, 5; and Elena, 9. They and their father, Jose Olguin, were found about 25 miles from Saginaw in Rush Township.

"I'm just so thankful to God the children are safe. The prayers were answered," said Woodrow Wilson II, a longtime friend of Erica Olguin's.

Jose Olguin, 35, drove with the girls to visit relatives in Elkhart, Ind., on Monday evening before the discovery of his wife's body, Luty said.

A woman heading south on Michigan 52 who had heard of the disappearance because of the Amber Alert spotted the car and called state police, said Sgt. Izzy Fuentes at the agency's Corunna post.