The school, which is between Spokane and Rockford, has 327 students, according to media reports. Spokane Public Schools said on Twitter that all schools in the area are "being put into adjusted lockdown as a prudent step".
After the shooting, all of the school's students were evacuated.
Officials say the suspect will appear in Spokane County juvenile court at 1:30 p.m. Thursday. "Today he made a decision to bring guns to school including a rifle which was stored in his large duffel bag and a handgun inside his coat pocket".
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.
As the suspect's name circulated online and in local press, the Spokesman-Review reported that he had a well-known history of firing guns on his YouTube channel. In addition to the high school, the middle and elementary schools were placed in lockdown.
Providence Sacred Heart Medical Centre and Children's Hospital received three paediatric patients, spokeswoman Nicole Stewart said.
The sheriff said the shooter fired several more rounds, hitting other students, before a school custodian ordered him to surrender.
The shooter was stopped by a janitor at the school.
"It's frightening, I think that's a point anyone can understand", Moore said.
Investigators are trying to determine whether bullying was the main motive in the shooting.
Sharpe was armed with two guns, witnesses said, according to the Spokesman-Review.
A call to the school was not immediately returned. She said she crouched on the floor when the shooting began.
A two-lane highway into the town of about 500 people near the Idaho border was clogged as anxious parents sped to the school.
"I heard this really loud noise, I thought someone had dropped something super heavy", Freeman junior Marcus Morphy told CNN affiliate KAYU-TV.
He called me and said, Mom, there are gunshots. "We love you and are dedicating tonight's show to the victims of today's tragic events, their family and friends, and everyone at Freeman High School", said the Tweet.
It was then that a courageous custodian put his life on the line, attempting to convince Sharpe to stop the madness, the Associated Press reports. She commended the school district for its communication.
A Washington State Patrol trooper called Wednesday the "worst day" in his law enforcement career after responding to his "own kids school for [an] active shooter".
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