US President Barack Obama said "There is not a parent in America who does not feel the same overwhelming grief as I do" after 27 people, including 18 children, were killed in a mass shooting at an elementary school in Connecticut.
In an emotional address to the nation from the White House, Mr Obama said that "as a country, we have been through this too many times".
Mr Obama spoke as police continued to investigate the circumstances behind the mass shootings at Sandy Hook Elementary School in Newtown, about 60 miles (96km) north-east of New York City.
Mr Obama, referring to Connecticut state governor Dannel Malloy, continued: "I offer Governor Malloy my condolences on behalf of the nation, and made it clear he will have every single resource that he needs to investigate this heinous crime, care for the victims, counsel their families.
"We endured too many of these tragedies in the past few years. And each time I learn the news, I react not as a president, but as anybody else would, as a parent. And that was especially true today. I know there is not a parent in America who doesn't feel the same overwhelming grief that I do.
"The majority of those who died today were children. Beautiful little kids between the ages of five and 10 years old."
The President paused for some seconds and wiped away tears before continuing: "They had their entire lives ahead of them. Birthdays, graduations, weddings, kids of their own. Among the fallen were also teachers, men and women who devoted their lives to helping our children fulfil their dreams.
"So our hearts are broken today. For the parents, and grandparents, sisters and brothers of these little children, and for the families of the adults who were lost.
"Our hearts are broken for the parents of the survivors as well, for, as blessed as they are to have their children home tonight, they know that their children's innocence has been torn away from them too early, and there are no words that will ease their pain."
Police were called to Sandy Hook Elementary School at around 9.40am local time (14.40GMT) after reports that a gunman had entered the school.
The suspect in the attack had links to the school, a law enforcement official said. Police said the gunman was also found dead inside the building.
A law enforcement official confirmed that he died from a self-inflicted gunshot wound.
The official named the suspect as 24-year-old Ryan Lanza and that his younger brother was being held for questioning as a possible second gunman.
The official said the men's mother, Nancy Lanza, worked at the school as a teacher.
He also said Ryan Lanza's girlfriend and another friend were missing in New Jersey.
If the death toll is confirmed, it would be one of the worst school shootings in the country's history.
Mr Obama continued: "As a country we have been through this too many times - whether its an elementary school in Newtown, in a shopping mall in Oregon, or a temple in Wisconsin, or a movie theatre in Aurora, or a street corner in Chicago - these neighbourhoods are our neighbourhoods, 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, regardless of the politics.
"This evening Michelle and I will do what I know every parent in America will do, which is hug our children a little tighter, and and we'll tell them that we love them, and will remind each other how deeply we love each other. But there are families in Connecticut who cannot do that tonight. And they need all of us right now."
The President left the briefing without taking any questions from the media.