An out-of-control driver killed two little kids in front of their horrified moms in a Brooklyn crosswalk Monday — with one tot dragged about 100 feet down the block while still in his stroller, authorities said.

The other child — the 4-year-old daughter of Broadway actress Ruthie Ann Miles, 34, of Park Slope — was run over and died, while her pregnant mom was also injured in the tragic wreck, sources said.

Miles “was bleeding from her head. They had to cut her coat off,’’ bystander Leah Finnegan said.

Miles’ daughter Abigail “was flat on her back, and when the ambulance came, they were giving her CPR,’’ added a witness, June Clark-Smith.

“I ran to the [mom], telling her, ‘Please, Miss, stay down.’ … She tried getting up on her knees and fell back down.’’

Miles — who won a Tony Award in 2015 for her role in “The King and I” — was in critical but stable condition in the intensive care unit at New York-Presbyterian Brooklyn Methodist Hospital.

Miles was heading from a church event at a nearby community center with the mother of the 1-year-old boy in the stroller — who ran up to her dying child after the crash, knelt beside his body and frantically tried to revive him, a witness said.

“The mom was sitting there next to him screaming,’’ fourth-year medical student Andrew Macaluso, 26, told The Post. “She was just kind of, ‘Oh, God, this can’t be happening! Tell me this isn’t happening! What’s going on?’”

Law enforcement sources said there is video surveillance footage from the scene, and it was unclear whether the driver had the light.

Dorothy Bruns, 44, told cops she was trying to avoid hitting a car and swerved out of the way. She remembers waking up behind the wheel but was unaware that she had hit anyone. Police sources said Bruns would not be held and was free to go, at least for now.

Additional reporting by Nick Fugallo and Shari Logan