NEWTOWN, Conn. -- A man killed his mother at their home and then opened fire Friday inside an elementary school, massacring 26 people, including 20 children.
Youngsters cowered in fear to the sound of gunshots echoing through the building and screams coming over the intercom.
The 20-year-old killer, carrying two handguns, committed suicide at the school, bringing the death toll of his rampage to 28, authorities said.
The incident, coming less than two weeks before Christmas, was the nation's second-deadliest school shooting, exceeded only by the Virginia Tech massacre that left 33 people dead in 2007.
Police shed no light on the motive for the attack on two classrooms. The gunman was believed to suffer from a personality disorder, one law enforcement official said.
Panicked parents looking for their children raced to Sandy Hook Elementary School in Newtown, a prosperous community of about 27,000 people 60 miles northeast of New York City.
Police told youngsters at the kindergarten-through-fourth-grade school to close their eyes as they were led from the building.
Schoolchildren -- some crying, others frightened -- were escorted through a parking lot in a line, hands on each other's shoulders.
Law enforcement officials speaking on condition of anonymity said that Lanza killed his mother, Nancy Lanza, then drove to the school in her car with at least three guns, including a high-powered rifle that he apparently left in the back of the vehicle, and shot up two classrooms around 9:30 a.m.
Authorities gave no details on exactly how the attack unfolded, but police radio traffic indicated the shooting lasted only a few minutes.
Students and their parents described teachers locking doors and ordering the children to huddle in a corner or hide in a closet when shots echoed through the building.
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 utter a word.
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."
Also, a custodian ran around warning people there was a gunman on the loose, 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.
Connecticut State Police Lt. Paul Vance said officers arrived instantaneously, immediately entered the school, searched it completely and found Lanza dead.
In addition to the 20 children, six adults were killed at the school; the principal is believed to be among the dead. A woman who worked at Sandy Hook was wounded.
A law enforcement official speaking on condition of anonymity said investigators believe Lanza attended the school several years ago but appeared to have no recent connection to the place.
At least one parent said Lanza's mother was a substitute teacher there, but her name did not appear on a staff list and the law enforcement official said investigators were unable to establish any connection so far between her and the school.