Two years ago this week, at Sandy Hook Elementary School, 20 children and six adults were killed in one of the deadliest school shootings in our nation's history. I will never forget the horror of how those children died - shot at close range with a high-powered rifle, with each child hit as many as 11 times, as a shooter fired more than 150 rounds of ammunition within five minutes. The tragedy was magnified by the realization of what could have happened if the killer had more time - given the time and capacity, he would have killed hundreds of children.

This week we recognize the loss of the children killed at Sandy Hook and the grief of their families and community. But this week also provides an opportunity to take stock of the past two years and the work we have ahead of us.

Since Sandy Hook, there have been more than 95 school shootings in the United States. According to statistics from the Centers for Disease Control and Prevention, compiled by Everytown for Gun Safety, there were 1,453 gun deaths in Pennsylvania in 2012. The numbers are staggering, and the refusal of some in Congress to take action is inexcusable.

We should be taking any steps within our power to ensure that our children are safe in their schools and parents can feel at peace knowing that their children are protected. In pursuit of that goal, in April 2013, the Senate took up a bipartisan set of proposals that would have expanded background checks for firearms sold at gun shows and on the Internet, improved the ability of law enforcement to tackle the problem of illegally transferred guns, and limited possession of certain high-capacity ammunition magazines and military-grade weapons.

I support the Second Amendment. Pennsylvania has a rich tradition of hunting, and I believe that people should be able to have guns for protection, sporting, and collection. But I also believe we need commonsense proposals to help keep powerful weapons out of the hands of wrongdoers without infringing on the fundamental Second Amendment rights of law-abiding gun owners.

Like many of my colleagues and millions of Americans, I am deeply disappointed that these measures did not pass, particularly in light of the overwhelming public support they enjoyed. I understand that some of my colleagues believe that these votes were conclusive - that there simply wasn't sufficient support among elected officials, and that the Senate functioned as it was intended. But I cannot in good conscience believe that Congress has satisfied our duty to ensure safety for our nation's children.

I truly believe that all of my colleagues are invested in protecting America's children from violence. We have an abiding obligation to come together in this shared commitment, to find common ground among the many proposals that have been introduced to address this crisis. We have before us a wide range of possibilities to address firearm violence: from renewed examination of the critical importance of background checks to laws that facilitate enforcement of existing restrictions; from bans on certain weapons to increased safety hardware on firearms; and from funding for research on gun violence to resources for mental health.

While no one piece of legislation could stop every tragedy, each may contribute to a safer society. Congress owes it to those who have been affected by firearm violence to consider each proposal fully. I refuse to believe that nothing more can be done.

Like so many Americans, I cannot forget or ignore the memory of Newtown. We can never recover the lives lost at Newtown, or the reported 30,000 lives that have been lost to firearms across our country since. But we cannot afford to wait for another tragedy to revisit this issue - every day that passes is an opportunity. Congress should take this opportunity, and act with the urgency our children deserve.