The gun attack on a country music festival Sunday in Las Vegas killed more than 50 people and injured more than 500 others.
After listing the many acts of heroism during the shooting, Sanders choked up reflecting on how those men and women who lost their lives will be remembered.
"The Gospel of John reminds us that there is no greater love than to lay down one's life for a friend," she said during the White House press briefing. "The memory of those who displayed the ultimate expression of love against an unimagined act of hate will never fade."
She added: "Their examples will serve as an eternal reminder that the American spirit cannot and will not ever be broken. In the days ahead, we will grieve as a nation we will honor the memory of those lost as a nation and we will come together united as one nation, under God, indivisible."
Earlier, President Donald Trump used a solemn address from the White House to call for unity in the aftermath of the deadliest mass shooting in modern US history
, calling it an "act of pure evil."
"We cannot fathom their pain, we cannot imagine their loss," Trump said of those who lost loved ones in the massacre.
But Sanders eschewed questions about support for stricter gun laws, saying the White House has been focused on "bringing our country together," not "the policy part."
Many Democrats, including Sen. Chris Murphy of Connecticut, have sought to press fellow lawmakers into action, however.
"To my colleagues: your cowardice to act cannot be whitewashed by thoughts and prayers," tweeted Murphy, who has pressed for stricter gun laws since the Sandy Hook massacre. "None of this ends unless we do something to stop it."
Sanders told reporters that having a debate on gun control is "not the place that we're in at this moment."
"There's a time and place for a political debate, but now is the time to unite as a country," Sanders said. "There's currently an open and ongoing law enforcement investigation, a motive is yet to be determined and it would be premature for us to discuss policy when we don't fully know all the facts or what took place last night."
Trump, however, has not always waited to inject politics into a mass shooting.
After a 2015 terrorist attack in San Bernardino, California, that killed 14 people, Trump quickly called for a "total and complete" ban on Muslims entering the United States.
Sanders looked to explain the split: "There is a difference between being a candidate and being the President."
"We haven't had the moment to have a deep dive on the policy part," Sanders said. "We have been focused on the fact that we had a severe tragedy in our country and this is a day of mourning, a time of bringing our country together, that has been the focus on the administration this morning."
But Trump also failed to wait last month following an explosion on one of the London's Underground trains.
"Another attack in London by a loser terrorist," the President tweeted. "These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!"