(CNN) -- The video shows a gold sedan entering a bend when the rear driver's-side door swings open and a child, still strapped in her car seat, tumbles out onto the street.
Captured in Mankato, Minnesota, it's now a key piece of evidence as the mother faces child endangerment and other charges.
Somehow, the child was not injured in last Monday's incident. A motorist, identified by CNN affiliate WCCO as Chad Mock, who had been following the sedan with his dashboard camera rolling, pulls up behind the child, exits his vehicle and signals for an oncoming car to slow down.
Maimuna Hassan, the girl's 40-year-old mother, continues down the street, apparently unaware her daughter is no longer in the car. She returned to the scene upon realizing it, Mock and police said.
The child, according to a probable cause statement, is about 2 years old.
Wearing a pink coat with her legs and left arm pointed skyward, the girl remains in the street, near the entrance to a grocery store, until Mock picks up the car seat and carries her to safety. The remnants of what appears to be a seat belt dangles from the child's seat.
"I think there's times we hear about this, but we don't actually have the opportunity to have footage of it," Mankato Police Cmdr. Daniel Schisel told WCCO. "It's amazing that this child didn't have any injuries."
The responding officer said he found no latch strap to secure the child seat in the car, though Hassan's 2004 Honda Civic is latch compatible, the probable cause statement says. The car seat's chest straps were also unbuckled, the officer reported, and the rear driver's side door was latched but not fully closed.
While the girl was properly strapped into her car seat, it appears the car seat wasn't thoroughly secured inside the car. Police do not know why the door swung open, WCCO reported.
Through an interpreter, Hassan told police she "was driving the vehicle; the door popped open; the car seat rolled out; the child was secured and must have unlocked it; drove up the street to park your car in the roadway; and walked back to the scene," according to the probable cause statement.
Court records indicate police charged Hassan on Thursday with one count of endangering a child in a situation that could cause harm or death and one count of not fastening a child passenger-restraint system.
Both are misdemeanors. The endangerment charge is punishable by up to a year in prison and a $3,000 fine.
Hassan is also charged with operating a car with only a learner's permit and without a licensed driver at least 21 years old in the car, also a misdemeanor.
Mock on his Facebook page, called the girl "very lucky" and wrote that if he hadn't seen it happen, he'd "never have believed it."
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