NEWTOWN, Connecticut (AP) -- A gunman killed 26 people, including 20 young children, at a Connecticut school Friday morning in one of the worst school shootings in the country's history .
Frightened students who were rushed from the building by police were told to close their eyes.
The 20-year-old killer, carrying two handguns, committed suicide at the school, bringing the toll to 28, authorities said.
The rampage in the northeastern state of Connecticut was at least the fourth big shooting spree in five months in the United States. It was by far the deadliest of the year and most heart-wrenching.
The children were among the youngest victims of a mass shooting in recent history.
Frightened students who were rushed from the building by police were told to close their eyes. Children -- some crying, others looking frightened -- were escorted through a parking lot in a line, hands on each other's shoulders.
"Our hearts are broken today," President Barack Obama said, wiping his eyes during brief comments to reporters in one of the most emotional public moments of his presidency. The children killed were just 5 to 10 years old, he said. "They had their entire lives ahead of them -- birthdays, graduations, wedding, kids of their own."
The national debate over the issue of gun control in America exploded once again. Obama said the U.S. had been "through this too many times" with recent mass shootings and that the country has to come together to take meaningful action, "regardless of the politics." He did not give details.
Police shed no light on the motive for the attack. The gunman was believed to suffer from a personality disorder and lived with his mother in Connecticut, said a law enforcement official who was briefed on the investigation but was not authorized to publicly discuss it.
Law enforcement officials speaking on condition of anonymity said Adam Lanza killed his mother, Nancy Lanza, and then drove to the school in her car with three guns, including a high-powered rifle that he apparently left in the back.
Authorities said he shot up two classrooms but otherwise gave no details on how the attack unfolded.
The attack at Sandy Hook Elementary School, just two weeks before Christmas, was the nation's second-deadliest school shooting, exceeded only by the Virginia Tech university massacre in 2007 that left 32 dead.
This time, the victims were far smaller. Children told their parents they had heard bangs and, at one point, a scream over the intercom. Teachers ordered them to hide in closets or corners.
State police Lt. Paul Vance said 28 people in all were killed, including the gunman, and one person was injured.
Lanza's older brother, 24-year-old Ryan, of Hoboken, N.J., was being questioned, but a law enforcement official said he was not believed to have had any role in the rampage.
Investigators were searching his computers and phone records, but he told law enforcement he had not been in touch with his brother since about 2010.
The officials spoke on the condition of anonymity because they were not authorized to speak on the record about the unfolding investigation.
Adam Lanza and his mother lived in a well-to-do part of Newtown where neighbors are doctors or hold white-collar positions at companies such as General Electric, Pepsi and IBM.
At least three guns were found -- a Glock and a Sig Sauer, both pistols, inside the school, and a .223-caliber rifle in the back of a car, authorities said. A law enforcement official speaking on condition of anonymity said some of the guns used in the attack may have belonged to Lanza's mother, who had legally purchased five weapons.
The shooting shocked a tranquil community of 27,000 people in one of the wealthiest counties in the U.S., about 60 miles (96 kilometers) northeast of New York City.
On Friday afternoon, family members were led away from a firehouse that was being used as a staging area, some of them weeping. One man, wearing only a T-shirt without a jacket, put his arms around a woman as they walked down the middle of the street, oblivious to everything around them.
Another woman with tears rolling down her face walked by carrying a car seat with a young infant inside and a bag that appeared to have toys and stuffed animals.
Robert Licata said his 6-year-old son was in class when the gunman burst in and shot the teacher.
"That's when my son grabbed a bunch of his friends and ran out the door," he said. "He was very brave. He waited for his friends."
Licata said the shooter didn't say a word.
Stephen Delgiadice said his 8-year-old daughter heard two big bangs, and teachers told her to get in a corner. His daughter was fine.
"It's alarming, especially in Newtown, Connecticut, which we always thought was the safest place in America," he said.
Theodore Varga said he was in a meeting with other fourth-grade teachers when he heard the gunfire, but there was no lock
on the door.
He said someone turned on the public address system so that "you could hear the hysteria that was going on. I think whoever did that saved a lot of people. Everyone in the school was listening to the terror that was transpiring."
Also, a custodian went running around, warning people there was a gunman in the school, Varga said.
"He said, `Guys! Get down! Hide!"' Varga said. "So he was actually a hero." The teacher said he did not know if the custodian survived.
Varga said he tried to kick out an air-conditioning unit in the window so the five teachers in the room could escape, but he only managed to knock out the wood next to it, and the space wasn't big enough for all of them to squeeze through.
He said he smelled gun smoke in the halls as he ran out to escape through a door. Varga then went around to help three other teachers climb out of the window of the first-floor room they had been in.
Mergim Bajraliu, 17, heard the gunshots echo from his home and ran to check on his 9-year-old sister, who was fine. He said she heard a scream come over the intercom at one point. He said teachers were shaking and crying as they came out of the building.
"Everyone was just traumatized," Bajraliu said.
Richard Wilford said his 7-year-old son, Richie, said he heard a noise that "sounded like what he described as cans falling."
The boy told him a teacher went out to check on the noise, came back in, locked the door and had the kids huddle in the corner until police arrived.
"There's no words," Wilford said.
Melissa Makris said her 10-year-old son, Philip, saw what looked like a body under a blanket as he fled the school.
The shootings instantly brought to mind episodes such as the Columbine school massacre in Colorado that killed 15 in 1999.
"I think as a society, we need to come together. It has to stop these senseless deaths," Columbine principal Frank DeAngelis said Friday.
Already this year, a gunman killed 12 people at a Colorado theater, and another gunman killed six people before killing himself at a Sikh temple in Wisconsin.
"We have endured too many of these tragedies," Obama said. He addressed reporters in the James S. Brady Press Briefing Room, named in honor of the former White House press secretary who was shot in the assassination attempt on Ronald Reagan in 1981. Brady and his wife, Sarah, have become activists for gun control measures.
"If now is not the time to have a serious discussion about gun control and the epidemic of gun violence plaguing our society, I don't know when is," one member of Congress, Rep. Jerrold Nadler, said in a statement.
Overseas, there was both shock and sympathy.
In a public statement addressed to Obama, French President Francois Hollande said he was "horrified."
British Prime Minister David Cameron said "it is heartbreaking to think of those who have had their children robbed from them." Queen Elizabeth II sent a message Obama saying she was saddened by the "dreadful loss of life."
Associated Press writers Jim Fitzgerald in Newtown, Pete Yost in Washington, D.C., Tom Hays in New York and Michael Melia in Hartford contributed to this report.