The awful shooting in a small Connecticut town has raised disturbing questions, but has also placed a spotlight on America's thriving gun business.
Taking a look at Black Friday just last month, U.S. shoppers weren't just buying toys and electronics, they were also buying a record number of guns.
On that single day, Nov. 23, the FBI did computerized background checks on more than 154,000 purchases of firearms. If you examine the month of November as a whole, Americans tried to buy 2 million guns.
There are more gun dealers and gun stores than there are major supermarkets.
Even though the majority of gun users are law abiding citizens, authorities say the large number of guns in circulation guarantees that disturbed people will be able to obtain them.
Adam Lanza used a Bushmaster .223 semi-automatic rifle at close range to kill 20 children and six adults at Sandy Hook Elementary School in Newtown, Conn., on Friday.
Two handguns were also found at the scene, but state officials described the Bushmaster as the killer's primary weapon. A fourth weapon was found nearby. The weapons discovered at the school apparently belonged to a family member, possibly his mother, according to authorities.
Lanza, 20, forced his way into Sandy Hook on Friday morning and killed 20 children and six adults before committing suicide. He drove to the school after shooting his mother in the face at their home.
The weapons that police recovered from the scene included a Glock 9-mm handgun, a Sig Sauer 9-mm handgun and a Bushmaster rifle. Police also found .223 shell casings. Lanza was wearing a bullet-proof vest.
The shooter's mother, 52-year-old Nancy Lanza, had five weapons registered to her, including a Glock, a Sig Sauer, and a Bushmaster rifle.
Bureau of Alcohol, Tobacco, Firearms and Explosives on-scene commander in Newtown, Gene Marquez, told ABC News that in the four-county area around the small Connecticut town, 400 gun dealers are open for business. Within 10 miles of Sandy Hook Elementary, Marquez said there are 36 gun dealers.
According to ABC sources, the Sandy Hook shooter Adam Lanza had bought two hand guns and an assault rifle legally.
Former FBI Agent Brad Garrett says it's fairly easy to purchase a firearm in the United States.
"Unless you have a felony conviction or you're adjudicated by a court to be deemed mentally incompetent ... you have ready access to firearms," said Garrett.