Nancy Lanza, in a 2012 photo that a relative saved from Facebook.

NEWTOWN, Conn. -- The mother of the suspected Sandy Hook Elementary School gunman, herself slain at the outset of the murderous rampage, was an avid gun enthusiast who liked to take her sons to the shooting range to practice their marksmanship, a friend tells NBC News.

Dan Holmes, a local landscaper and a friend of Nancy Lanza, mother of 20-year-old suspected gunman Adam Lanza, said she also was a collector.

“She had a pretty extensive gun collection,” Holmes said. “She was a collector, she was pretty proud of that. She always mentioned that she really loved the act of shooting.”

Holmes recalled that she said she was able to “focus in” while shooting.

Federal officials tell NBC News that Adam Lanza took three weapons with him to the school – two pistols, a Glock and a Sig Sauer, and a Bushmaster .223-caliber semi-automatic assault-style rifle – all of which were registered to Nancy Lanza.

It is unclear whether all the guns were used in the attack. At a news briefing on Saturday, Chief Medical Examiner Dr. H. Wayne Carver II, who led the team that autopsied the victims, said, “All the (injuries) … I know of were caused by the rifle.”

The Associated Press reported that authorities investigating the school shooting later recovered additional weapons -- a Henry repeating rifle, an Enfield rifle and a shotgun. It was not clear where those weapons were found.

Holmes, Nancy Lanza’s friend, said the 52-year-old single mother also frequently talked about how she was worried about Adam.

Investigators and former classmates of Connecticut school shooter Adam Lanza say he was bright, but extremely shy and remote. NBC's Pete Williams reports.

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She talked about “how he was an unstable kid,” he said. “She would talk about that. “She was very protective of him. I don’t … think she ever got major help for him. She just tried to handle it on her own. It was something she was definitely disturbed about.”

Meantime, federal agents visited a gun shooting range near Newtown, Conn., in an effort determine if Adam Lanza visited in the months before the attack, which could indicate he was planning or practicing for the bloodbath he carried out early Friday.

Dean Price, director of the Wooster Mountain Shooting Range near Newtown, told NBC News that he was visited by agents from the federal Bureau of Alcohol ,Tobacco, Firearms and Explosives on Friday night and that they searched through his records for any evidence that the younger Lanza had signed in there in 2012. They also checked to see if he had used the name of his older brother, Ryan, Price said.

There was no indication that Adam Lanza had used the shooting range, which requires customers to sign in and show identification prior to using the facility, Price said.

Agents also have been checking local firearms dealers to see if Adam Lanza purchased or attempted to purchase weapons or ammunition prior to the shooting.

Law enforcement officials said members of the public reported they thought they saw Adam Lanza trying to buy a rifle at a Dick’s Sporting Good store in Danbury, but investigators have yet to confirm that.

NBC News' Senior Investigative Correspondent Lisa Myers and Justice Correspondent Pete Williams contributed to this report.

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