Credit: Newsday / Matthew Chayes

Two young children were killed and two others injured — including one of the kids' pregnant mother — after being struck by a car in Park Slope Monday afternoon.

All of the victims were pedestrians, officials said, in a crash that happened near the intersection of Fifth Avenue and Ninth Street in Brooklyn about 12:40 p.m., according to police and fire officials.

The children, a boy and a girl, who police believed were ages 1 and 4, respectively, were pronounced dead at the scene. The girl's mother was taken to NewYork-Presbyterian Brooklyn Methodist Hospital, according to the FDNY. She and a fourth victim, an adult female, were in stable condition, police said.

The boy was in a stroller, which appeared to be dragged with the car, a white Volvo. Police did not know if the boy remained in the stroller as it was pulled about halfway down the block, between Fourth and Fifth avenues.

The female driver, 44, believed she'd had a medical episode and was being evaluated, police said.

"There's a full investigation underway," Mayor Bill de Blasio said at an unrelated news conference on Monday. "This loss of life is tragic and painful for all of us, especially parents."

June Clark-Smith, 60, was standing by the intersection when the crash occurred and ran over to the visibly pregnant mother who, she said, was lying on the ground and bleeding badly. The mother kept calling for "my baby."

“She got up on one knee,” Clark-Smith said. “I said, 'please, the ambulance is here, they’re taking care of the baby.' I was just so scared. I was just praying."

Dan Brady, 30, said he was working nearby when he heard "a pretty distinctive sound, like a thud."

He said he ran outside and saw a group surrounding one of the children in the middle of the street.

"I kinda turned away," Brady said. "You don't expect something like this."

Transit advocates began planning a rally for safer streets, to be held Tuesday outside of the Park Slope YMCA, which the mayor frequents and isn't far from the site of the crash. Paul Steely White, the executive director for Transportation Alternatives, said he’d be at the mayor’s gym in the morning.

White plans on following up with another, Transportation Alternatives-planned rally outside of City Council offices on Broadway at noon on Tuesday, where the group will call on the Council to explore legislation to create comprehensive street design standards under Vision Zero for more protected space for pedestrians and cyclists while slowing vehicular speeds.

"Like all New Yorkers, we’re horrified by this,” White said of the crash. “We as a city must come together to grieve but to take action to prevent this from happening again.”

The intersection was the scene of one pedestrian fatality in 2016 and 10 traffic injuries since 2014, according to city data as of January 2018.

With Vincent Barone

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