Police continued searching Monday for a gunman who drove up and opened fire at a child's birthday party in Fort Worth, Tex., killing a woman and 5-year-old girl and wounding four others, authorities said.

Annette Stevenson, 48, died at the scene Sunday night and Queshawn Stevenson, 5, who had been shot in the neck and stomach, died early Monday at a hospital, according to the Tarrant County Medical Examiner's Office. It's unclear whether the two are related.

Four other people were wounded — a woman and three children, including the birthday girl who turned 9 on Monday, authorities said.

Winifred King, a spokeswoman for Cook Children's Medical Center in Fort Worth, said the three children's families had asked that no information be released about their conditions. Medical information on the wounded adult was not immediately available Monday.

A man in a car drove up and began firing as the party was being held at Annette Stevenson's duplex, but police were still trying to determine if the home was being targeted.