Senate leaders mourn Sandy Hook 'massacre' victims in moment of silence

“In the coming days and weeks, we will engage in a meaningful conversation and thoughtful debate about how to change laws and culture that allow violence to grow,” Reid said on the floor Monday. “We have no greater responsibility than keeping our most vulnerable and most precious resource — our children — safe. And every idea should be on the table as we discuss how best to do just that.”

The gunman, 20-year-old Adam Lanza, used a high-powered rifle and had an arsenal of hundreds of rounds of especially deadly ammunition, reports have stated. He killed himself about 10 minutes after starting the attack.

The Associated Press reported that Lanza is believed to have used a Bushmaster AR-15 rifle in the school attack, a civilian version of the military's M-16. Some AR-15s were outlawed as part of the 1994 assault weapons ban. But that law expired in 2004, and Congress did not renew it after heavy pressure from gun-rights lobbyists.

Senate Minority Leader Mitch McConnell (R-Ky.) said the incident “doesn’t just break our hearts, it shatters them.”

“Three days after the horrors of Newtown, we’re all still reeling from what happened,” McConnell said. “Any time there’s a shooting like this we’re crushed with sorrow, but there’s no escaping the fact that the massacre at Sandy Hook Elementary stands out for its awfulness. The murder of so many little children and the adults who tried to save them doesn’t just break our hearts, it shatters them.”