In an appearance on NBC's "Meet the Press," LaPierre, NRA executive vice president, said "there weren't enough good guys with guns" to stop Aaron Alexis, the shooter who killed 12 people at the Navy Yard.
"When the good guys got there, it stopped," LaPierre said in his first televised interview since the rampage.
He said more personnel should be armed at military facilities, including retired military personnel, to protect against such attacks.
"We need to look at letting the men and women that know firearms and are trained in them, do what they do best, which is protect and survive," he said.
He also argued against the United States' treatment of the mentally ill, saying they should be committed to treatment facilities.
"They need to be committed is what they need to be, and if they're committed, they're not at the Navy Yard," LaPierre said. "So the Aurora shooter in Colorado gets checked and is cleared, the Tucson shooter gets checked and gets cleared, Aaron Alexis go through the federal and state check and gets cleared."