Report: Conn. Gunman Had an 'Altercation' With School Staff the Day Before Massacre

First responders gather at the scene of a mass school shooting at Sandy Hook Elementary in Newtown, Conn. on Friday, Dec. 14, 2012. (Getty Images)

​Editor's note: ​See update below.

The gunman who massacred 26 children and adults then killed himself at a Newtown, Conn. elementary school reportedly had an "altercation" with four school staff members the day before, according to NBC News. It was not clear what the argument was about.

NBC reported that three of the four Sandy Hook Elementary staff member died Friday when 20-year-old Adam Lanza opened fire. The fourth was not at school that day and was being interviewed by investigators.

Two days earlier, Lanza reportedly tried to purchase a rifle from a sporting goods store in nearby Danbury, Conn., but was blocked by the state's gun sale waiting period.

Authorities have said Lanza first shot his mother, Nancy Lanza, at home, then used her car to drive to the school with at least three of her guns and forced his way in.

It's unclear precisely what Nancy Lanza's link to Sandy Hook Elementary was, according to the Associated Press. Early reports said she was a teacher, then at least one parent said she was a substitute, but her name does not appear on staff lists and investigators have not stated a connection. According to NBC, Adam Lanza was once a student at the school and shot 20 children at close range when he made it inside.

All the victims' bodies were removed from the school and taken to the medical examiner's office, police said Saturday. All the victims have been identified and authorities were preparing to release a written list of names and birth dates.

​Update, Sunday:​ Connecticut State Police Lt. Paul Vance said Saturday there was no report of any confrontation between Lanza and school staff in the days before the shooting. NBC News has maintained its report.