A heartbreaking and unforgettable tragedy has beset Newtown, a small town in Connecticut, where a gunman slaughtered 28 people, including 20 children, at an elementary school Friday.

Immersed in mixed feelings of fear, sadness and despair, residents cried, prayed and hugged each other, unable to believe it was real.

Some of the victims' families were hopeful their loved ones had just been wounded and taken to hospital.

They would be released soon, their family members prayed, until the hope was dashed by a police announcement.

Paul Vance, a spokesman of the state police, told reporters outside the Sandy Hook Elementary School that major crime detectives had begun documentation process on the case.

However, he still could not identify the gunman.

Mitchell, a young boy who lives near the school, told Xinhua his friend's brother witnessed the whole shooting and managed to make his way out.

He said, according to the witness, the gunman broke into a classroom, shot the teacher, and opened fire on the rest of the class.

"It's terrible; it's unbelievable; you wouldn't think anything like this would happen in such a small town," Mitchell said. "Everyone here are all friends; there are no strangers. The killer lives in Newtown, and he killed his mom and her class."

The killer was found dead inside the school building from an apparent self-inflicted gunshot wound, witnesses said.

Authorities found at least three guns at the scene, and a federal official said all the weapons recovered in the shooting were, according to state records, bought legally and registered to the gunman's mother.

Robert Weiss, a pastor of a nearby church, said he knew most of the victims' parents.

"It's a tough day. It's just a tragedy. I cannot explain and understand," he said. "There's no word that can express the magnitude... These are little kids."

All the churches in the town would open for services in the evening and people could stop by and pray, Weiss said.

"People need to get together, and support each other. I was asked here to support the family," he said.

Geoffery Davis, who has been praying in a nearby church, urged authorities to "do something" to prevent such tragedies from happening again.

"It's crushing... Young people have to see and the community has to see. The Congress has to step up to do something about this, at a priority level," he said.

According to Davis, a US journalist commented the gun problem was really a big problem in the country.

It is "a political issue" that had been discussed over and over again, he said.

"People look at it in two ways: some agree, some disagree, arguing that guns don't kill people; people kill people. Anyway it will be brought up to the front again," he said.