The victim accidentally struck the lawyer's car with the ball, authorities said.
"It was like being hit by a car," said a hamburger vendor injured in the strike.
The girl is the 12th child to be killed by gunfire in St. Louis since April, the local newspaper reports.
The actress debuted the first look of the titular character at a Disney fan club event on Saturday.
"Lt Col. Anne McClain has an accomplished military career, flew combat missions in Iraq and is one of NASA’s top astronauts," the space agency said..