NEWTOWN, Conn. -- In one of the deadliest mass shootings in American history, 27 people -- 20 of them children -- died Friday morning during a shooting at a Connecticut elementary school.

The shooter was one of the dead at Sandy Hook Elementary School in western Connecticut, about 60 miles northeast of New York City.

But the death toll in connection with the massacre is even higher. Police said a body was found at another location in Newtown, bringing the death toll to 28.

Connecticut state police Lt. J. Paul Vance said 18 children died at the school. Two others were taken to a hospital, where they died. Six adults were killed at the school. And the shooter was also found dead. One person was wounded.

Vance also said another person was found dead at a "secondary" location. Vance also said there were search warrants being served inside and outside of the state.

Vance said there were "a lot of things we cannot confirm or discuss."

"Our hearts are broken today," a tearful President Barack Obama, struggling to maintain composure, said at the White House. He called for "meaningful action" to prevent such shootings.

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.

The Associated Press reported the suspect in the Connecticut school shootings is Adam Lanza, 20, the son of a teacher at the school where the shootings occurred, a law enforcement official said Friday. A second law enforcement official says the boy's mother, Nancy Lanza is presumed dead.

A law enforcement official briefed on the investigation says the brother of the gunman has been "extremely cooperative" and is not under arrest.

The official tells The Associated Press that Ryan Lanza, of Hoboken, N.J., is still be being questioned but is not in custody and is not believed to have any connection to the school killings.

The official spoke on condition of anonymity because he was not authorized to speak publicly on the investigation.

The official says Ryan Lanza's computers and phone records were being searched but only "in an abundance of caution." He says Ryan told authorities he had not been in touch with his brother in recent years.

Earlier, another law enforcement official mistakenly transposed the brothers' first names.

Both officials spoke on the condition of anonymity because they were not authorized to speak on the record about the developing criminal investigation.

The first official said Adam Lanza is dead from a self-inflicted gunshot wound.

According to the second official, the suspect drove to the scene of the shootings in his mother's car. The shooting took place just after 9:30 a.m.

Three guns were found at the scene -- a Glock and a Sig Sauer, both pistols -- and a .223-caliber rifle. The rifle was recovered from the back of a car at the school, which is for kindergarten through fourth grade. The two pistols were recovered from inside the school.

One of the officials said earlier Friday that a girlfriend of one of the Lanza brothers and another friend were missing in New Jersey. Subsequently, the third official said police had talked with the girlfriend. One of the friends had to be reached in California, so it took some time.

The shooting appeared to be the nation's second-deadliest school shooting, exceeded only by the Virginia Tech massacre in 2007 in which 32 people died

Danbury Hospital confirmed it received three patients from the scene.

"I've never been more terrified in my life," said Sarah Walker Caron, whose young son, Will, was in the school." My heart was pounding. I couldn't race fast enough (to the school)." Walker Caron said she believes authorities are "doing the best they can." She said that she had only heard rumors at this point, and could not confirm them, but she had heard that there could still be children in the school. She also had heard unconfirmed rumors of a second shooter.

Richard Wilson, 36, of Sandy Hook, said he and his wife were home when they got the call that there was a shooting at their son's school.

Their son, Richie, 7, said the gun shots sounded like "really loud pots were banging."

"It's the most terrible moment of a parent's life -- you have no idea," Richard Wilson said.

Many parents walked down street holding hands with their children.

"I heard what happened on the news and I just headed here to get my son," said a mother, Maria Nascimento.

Audra Barth, another mother who has two children at Sandy Hook Elementary, "The parents were given no information. I was just at home going crazy. I didn't even know which school it was. I found out from media."

A reporter observed three state troopers with canines walking around the woods nearby, and parents leading their young children away from the scene.

It wasn't immediately clear how seriously anyone was injured. The Newtown Bee reports that "one child was carried from the school by a police officer, apparently seriously wounded. Other injuries are reported, and emergency personnel have set up triage facilities"

The school superintendent's office says the district has locked down schools to ensure the safety of students and staff.

The Newtown Bee newspaper posted a photo of a group of young students -- some crying, others looking visibly frightened -- being escorted by adults through a parking lot in a line, hands on one another's shoulders.

Police told reporters to stay out of the woods and stick to the road. Officers with weapons drawn were stopping cars and questioning motorists. They looked in car windows in a nearby parking lot.