Debora Seifert, a spokeswoman for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, said both Lanza and his mother fired at shooting ranges, and also visited ranges together.
"We do not have any indication at this time that the shooter engaged in shooting activities in the past six months," Seifert said.
Investigators have found no letters or diaries that could explain the attack.
Whatever his motives, normalcy will be slow in revisiting Newtown. Classes were canceled district-wide Monday, though other students in town were expected to return to class Tuesday.
Dan Capodicci, whose 10-year-old daughter attends the school at St. Rose of Lima Roman Catholic Church, said he thinks it's time for her to get back to classes.
"It's the right thing to do. You have to send your kids back. But at the same time I'm worried," he said. "We need to get back to normal."
Gina Wolfman said her daughters are going back to their seventh- and ninth-grade classrooms tomorrow. She thinks they are ready to be back with their friends.
"I think they want to be back with everyone and share," she said.
Newtown police Lt. George Sinko said whether to send children to school is a personal decision for every parent.
"I can't imagine what it must be like being a parent with a child that young, putting them on a school bus," Sinko said.
The district has made plans to send surviving Sandy Hook students to Chalk Hill, a former middle school in the neighboring town of Monroe. Sandy Hook desks that will fit the small students are being taken there, empty since town schools consolidated last year, and tradesmen are donating their services to get the school ready within a matter of days.
"These are innocent children that need to be put on the right path again," Monroe police Lt. Brian McCauley said.
With Sandy Hook Elementary still designated a crime scene, state police Lt. Paul Vance said it could be months before police turn the school back over to the district.
The shooting has put schools on edge across the country.
Anxiety ran high enough in Ridgefield, Conn., about 20 miles from Newtown, that officials ordered a lockdown at schools after a person deemed suspicious was seen at a train station.
Two schools were locked down in South Burlington, Vt., because of an unspecified threat. A high school in Windham, N.H., was briefly locked down after an administrator heard a loud bang, but a police search found nothing suspicious.
Lanza is believed to have used a Bushmaster AR-15-style rifle, a civilian version of the military's M-16. It is similar to the weapon used in a recent shopping mall shooting in Oregon and other deadly attacks around the U.S. Versions of the AR-15 were outlawed in this country under the 1994 assault weapons ban, but the law expired in 2004.
Private equity firm Cerberus Capital Management announced Tuesday it plans to sell its stake in Freedom Group, maker of the Bushmaster rifle, following the school shootings.
Cerberus said in a statement Tuesday that it was deeply saddened by Friday's events, and that it will hire a financial adviser to help with the process of selling its Freedom Group interests.
The outlines of a national debate on gun control have begun to take shape. At the White House, spokesman Jay Carney said curbing gun violence is a complex problem that will require a "comprehensive solution."