Friday's mass shooting at an elementary school in the state of Connecticut - the second worst such incident in U.S. history - was the latest to occur during President Barack Obama's first term.
The entrance to a shopping center in Tucson, Arizona in 2011... a crowded movie theater in Aurora, Colorado last July... and now, an elementary school filled with children in Newtown, Connecticut.
After each tragedy, Obama has offered words of comfort for families of those killed, and traveled to towns and cities to meet with and offer encouragement to survivors.
A few hours after first receiving word of the shootings in Connecticut, Obama came to the White House briefing room to deliver a statement laden with emotion.
Saying the nation has "endured too many of these tragedies," pausing twice and appearing near tears, he said the country must find a way to put an end to such violence.
"As a country we have been through this too many times, whether it is an elementary school in Newtown, or a shopping mall in Oregon, or a temple in Wisconsin, or a movie theater in Aurora, or a street corner in Chicago, these neighborhoods are our neighborhoods and these children are our children. And we're going to have to come together and take meaningful action to prevent more tragedies like this, and regardless of the politics," said Obama.
Since Obama was elected in 2008, there have been at least 10 mass shooting incidents, including those he referenced in his statement.
The Connecticut massacre was the second worst school shooting incident after 32 people were killed and 17 wounded at Virginia Tech in 2007.
After 13 people were killed last July by a gunman opening fire in a movie theater in Aurora, Colorado, the president urged Americans to reflect.
"I hope that over the next several days, next several weeks, and next several months, we all reflect on how we can do something about some of the senseless violence that ends up marring this country," he said.
In Tucson, Arizona, where a gunman took the lives of 6 people in 2011, and wounded 13, including a U.S. congresswoman, the president urged Americans not to allow that tragedy to intensify national divisions.
"We cannot and will not be passive in the face of such violence. We should be willing to challenge old assumptions in order to lessen the prospects of such violence in the future. But what we cannot do is use this tragedy as one more occasion to turn on each other," said Obama.
Gun control issue
The latest incident thrusts questions about gun control in the United States back into the national discourse.
Strengthening gun control laws is one of the most difficult social and political issues in the United States. Powerful lobbying groups such as the National Rifle Association, anti-gun groups, members of Congress, and the president are in the middle of the debate.
Whether Obama, using added political leverage from his reelection, and national anger over the latest tragedy, can move the country forward in the gun control debate, remains to be seen.
After the president's remarks about the Connecticut shootings, gun control advocates gathered for a candlelight vigil outside the White House.
Michael McBride is a pastor from California. He said Obama should use his State of the Union address next year to chart a course on gun control.
"Please lay out a plan of action of how we may address this scourge of gun violence in our communities," said McBride.
Bill Meffords from Virginia brought his two sons to the demonstration. He said the Connecticut shootings present Obama with an opportunity to energize gun control efforts, but he has to move quickly.
"If he waits and allows what has happened time and time again, if he allows the focus to be placed on other things, or the distraction of talking heads like the NRA and everybody else to take us away from what really is important here and that is saving lives, if he moves now I think he can," said Meffords.
President Obama's spokesman, Jay Carney, avoided any statements on the overall gun control debate, saying it was not a time to "engage in the usual Washington policy debates."
But in response to one question, he said the president remains committed to a pledge he made to work to renew the federal ban on assault weapons that was allowed to lapse in 2004.
A boy is comforted outside Sandy Hook Elementary School after a shooting in Newtown, Connecticut, December 14, 2012.
A police officer keeps guard from a hill top over looking Sandy Hook Elementary School. At least 20 people, including children, were killed on Friday when a shooter opened fire.
Parents leave a staging area after being reunited with their children following a shooting at the Sandy Hook Elementary School.
This satellite image provided by Google shows the Sandy Hook Elementary School in Newtown, Connecticut.
A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut.
The scene at Sandy Hook Elementary School in Newtown, Connecticut, December 14, 2012.
White House press secretary Jay Carney told reporters that President Barack Obama is receiving updates on the situation in Connecticut during the daily press briefing at the White House in Washington.
Family members embrace each other outside Sandy Hook Elementary School.