GEOFF BENNETT: Welcome to the "News Hour."

Police are still investigating the motive behind the deadly shooting at Silver Rail Elementary School in Bend, Oregon.

Officials say four people were killed, including three young children and a teacher.

Two of those victims were identified, 5-year-old Rhoam Summer and teacher Megan Lambert.

She was 25 years old.

AMNA NAWAZ: Police have identified the alleged shooter as 16-year-old Griffin J. John II.

He previously attended Silver Rail Elementary, where authorities said he was a special needs student.

They said that yesterday he attacked a special needs classroom before being killed at the scene himself.

William Brangham starts our coverage.

WILLIAM BRANGHAM: In Bend, Oregon, families huddle together, mourning those who've been lost, grieving yet another gun-related tragedy in America.

GOV.

TINA KOTEK (D-OR): No parent, no family, no community should have to have this kind of day.

WILLIAM BRANGHAM: Last night, people gathered in a park near the school to sing hymns and offer prayers.

The state's governor, Democrat Tina Kotek, tried to console the city.

GOV.

TINA KOTEK: Let's remember what matters and take care of each other because it's going to be hard.

But you have each other.

And I love you.

WILLIAM BRANGHAM: This all following a terrifying day in the Central Oregon town.

EMERGENCY DISPATCHER: For an active shooter at Silver Rail Elementary.

WILLIAM BRANGHAM: Police rushed to the scene yesterday within minutes after a suspect shot his way into Silver Rail Elementary School, reportedly with a shotgun.

He then shot and killed a teacher and three young students.

A 7-year-old and another teacher were taken to the hospital with critical injuries.

Ten-year-old Aizen recalled the moments he first heard the gunfire.

AIZEN, Student at Silver Rail Elementary School: I locked the door and I went back behind our lockers, as all my classmates did the same.

All of my classmates and my teacher were safe, but we were definitely scared, and most people were crying.

And it was really hard.

Late today, Bend's police chief, Mike Krantz, said at a press conference that the shooter broke through the school's security.

MIKE KRANTZ, Bend, Oregon, Police Chief: He fired multiple rounds into the glass panes in the doors to gain access to the school.

The suspect went directly into the classroom immediately to the left of the entry doors, where he fired as many as 15 rounds.

WILLIAM BRANGHAM: By the time police entered the school, the suspect was already dead.

The 16-year-old shooter's identity was confirmed today, and the shotgun he allegedly used was registered to his mother.

Authorities say he was killed by a bystander who'd seen the suspect enter the school, followed him in and shot him.

Multiple news reports identified that man as Kaylub Giamanco.

According to his mother, he has two daughters who attend Silver Rail.

Many local officials praised Giamanco's intervention.

And President Trump weighed in today, calling Giamanco a hero, adding -- quote -- "Otherwise, it would have been much worse.

It's a terrible thing, but thank goodness for a man that had a gun and knew how to use it."

Chief Krantz also addressed that man's role, describing what happened when he first entered the school.

MIKE KRANTZ: As he made entry through the forced open doors, he heard shooting and saw a teacher involved in a physical altercation with the suspect.

He then went to the classroom where the struggle was under way and fired his weapon, striking the suspect multiple times.

WILLIAM BRANGHAM: Outside Silver Rail earlier today, silence.

All schools in the district were closed for the day, yellow tape cordoning off the crime scene, flowers and candles and notes signaling the grief of so many.

Among those paying their respects was Brooke Olsen.

Her daughter is a kindergartner at the school.

BROOKE OLSEN, Parent: It didn't feel real.

It didn't feel like it could be happening here at our school.

And it's extremely painful.

And it's hard to understand.

We can't understand it.

And we're trying to grieve and process and recover.

WILLIAM BRANGHAM: The Associated Press marks this shooting as the 28th mass killing in the U.S.

this year.

For the "PBS News Hour," I'm William Brangham.