Friend tried to stop suspect shooter Caleb Sharpe at Washington high school

The heroic best friend of a 15-year-old gunman who was murdered as he tried to stop his shooting spree at a Washington high school on Wednesday and the high school custodian who eventually brought him down have been pictured.

Sam Strahan, 15, was shot in the head as he tried to persuade the suspected shooter, named by police as Caleb Sharpe, from killing classmates at Freeman High School in Rockford, Washington, on Wednesday (US time), the Daily Mail reported.

The suspect had posted videos online showing him playing with guns, including one where he pretends to hunt for a drug dealer.

Sam Strahan, left, died as he tried to stop the gunman on Wednesday. High school custodian Joe Bowen, right with his wife, was eventually able to convince the shooter to stop firing. Photo / Supplied

Classmates at Freeman High School in the tiny town of Rockford, south of Spokane, knew about the videos. Junior Paul Fricke told The Spokesman-Review newspaper that "we knew he had an assault rifle, because he uses it in his YouTube videos." Another student described the suspect as obsessed with previous school shootings.

The victim's grieving family have revealed that Sam was still mourning the loss of his father, who died in a car accident earlier this year, when he died.

After he was killed, Air Force veteran turned high school custodian Joe Bowen, 42, convinced the gunman to stop shooting for long enough for him to be brought down by police.

Three other teenage girls were injured in the shooting but are all "doing well" in hospital.

Both Sam and Joe, a married father-of-three, have been credited with saving lives with their efforts to stop the shooter.

The terror began shortly after 10am when the gunman tried to open fire with the first of two weapons he had brought to school in a black duffel bag.

That weapon jammed, a happenstance which police prevented more bloodshed, and he went on the next one.

Sharpe was seen being escorted in to a juvenile detention centre with a shaved head. Photo / KHQ TV

Sam, who other students said was Caleb's "best friend", approached him and tried to talk him out of the shooting spree.

"He tried to walk up and tell him, 'this isn't what you wanna do'," Spokane County Sheriff Ozzie Knezovich said on Wednesday.

He was coldly killed by a single bullet to the head and the gunman continued shooting before Bowen intervened.

It is not known what exactly he said to the teenager to get him to stop shooting, but police told KHQ he convinced him to stop shooting for long enough for police to arrive and arrest him.

Bowen did not respond to requests on Thursday morning.

Sheriff Knezovich previously said his efforts saved the lives of other students who were in the gunman's firing line.

Parents reunited with their children, leave Freeman High School hours after the school shooting left one student dead and three injured. Photo / AP

After the shooting, all of the school's students were evacuated.

Some then named Sharpe as the shooter and described how he'd been acting strangely in the weeks which preceded the shooting.

According to some teenagers who said they were friends with him, he had been watching documentaries about other school shootings and had passed around notes threatening to "do something stupid" that would get him killed.

Ambulances line up in the emergency area of Sacred Heart Hospital following the shooting. Photo / AP

People gather outside of Freeman High School after reports of the shooting at the school in Rockford. Photo / AP

As they were being evacuated, one student shared this photograph on Twitter of her class crouching on the floor. Photo / via Twitter

The Breaking Bad-obsessed teen had uploaded odd videos to YouTube in which he practiced shooting with a toy gun.

On social media, he shared self-loathing posts about depression and anxiety.

He was taken into a juvenile detention centre after the shooting and remains in custody.

Sam's family is fundraising for his mother and sister.