Newtown massacre gunman Adam Lanza forced his way into Sandy Hook Elementary School, where his youngest victims were shot at close range, law enforcement officials told NBC News.

The chilling details emerged as authorities prepared to release the names of the 20 children and six adults slaughtered Friday at the Connecticut school.

A team from the Medical Examiner’s office worked all night to identify the bodies, which were removed by Saturday morning, while officials notified parents. It could take at least two more days for investigators to finish combing over the crime scene.

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