Three other children were reported in stable condition and one in serious condition, WUSA-TV in Washington reported. The surviving children weren't identified but at least one was a brother of the dead girl.
Maria Anna Cruz-Lopez, 33, was backing her SUV into her driveway Thursday morning in Lewisdale, Md., police said. She apparently didn't see the children and then hit the accelerator instead of the brake.
Natalie Hernandez Cruz, 8, was injured by bricks that fell on her, police said, and died from those injuries.
Police had been called to the house earlier because Cruz-Lopez, believed to be an illegal tenant, was in a dispute with her landlord about leaving the property. Investigators said the dispute and the accident weren't connected.
Cruz-Lopez, who hasn't been charged with anything, hadn't been drinking or using drugs, investigators said.