UPDATE, 6 P.M.: Law enforcement officials had initially identified the Newtown shooting suspect as Ryan Lanza. They have since said the suspect is Adam Lanza, Ryan's brother. The boys' mother, Nancy Lanza, works at the school as a teacher.
NEWTOWN, Conn. (AP) -- A man opened fire inside the Connecticut elementary school where his mother worked Friday, killing 26 people, including 18 children, and forcing students to cower in classrooms and then flee with the help of teachers and police.
The death toll -- 26 victims plus the gunman -- was given to The Associated Press by an official who spoke on condition of anonymity because the investigation was still under way.
The shooting appeared to be the nation's second-deadliest school shooting, exceeded only by the Virginia Tech massacre in 2007, which left 32 people and the gunman dead.
Parents flooded to Sandy Hook Elementary School, about 60 miles northeast of New York City, looking for their children in the wake of the shooting. Students were told to close their eyes by police as they were led from the building.
A photo taken by The Newtown Bee newspaper showed a group of young students -- some crying, others looking visibly frightened -- being escorted by adults through a parking lot in a line, hands on each other's shoulders.
Students and staff were among the victims, state police Lt. Paul Vance said a brief news conference. He also said the gunman was dead inside the school, but he refused to say how many people were killed.
A law enforcement official briefed on the shooting said the gunman died from a self-inflicted gunshot wound and that one of the victims was the man's mother, a teacher. The official wasn't authorized to speak about the investigation.
A law enforcement official in Washington said the attacker was a 20-year-old man armed with a .223-caliber rifle. The official also said that police were searching a location in New Jersey in connection with the shootings. That official spoke on the condition of anonymity because the source was not authorized to speak on the record about the developing criminal investigation.
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."
He 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.
Danbury Hospital was the only hospital to take in victims from the shootings, admitting three patients. Doctors said at a news conference they cleared four trauma rooms to treat shooting victims.
Mergim Bajraliu, 17, heard the gunshots echo from his home and raced to check on his 9-year-old sister at the school. He said his sister, who was fine, 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," he said.
Richard Wilford's 7-year-old son, Richie, is in the second grade at the school. His son told him that 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 up in the corner until police arrived.
"There's no words," Wilford said. "It's sheer terror, a sense of imminent danger, to get to your child and be there to protect him."
Melissa Makris, 43, said her 10-year-old son, Philip, was in the school gym.
"He said he heard a lot of loud noises and then screaming. Then the gym teachers immediately gathered the children in a corner and kept them safe in a corner," Makris said.
The fourth-grader told his mother that the students stayed huddled until police came in the gym. He also told her that he saw what looked like a body under a blanket as he fled the school.
"He said the policeman came in and helped them get out of the building and told them to run," Makris said. "And they ran to the firehouse."
The White House said Barack Obama was notified of the shooting and his spokesman Jay Carney said the president had "enormous sympathy for families that are affected."
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.