Teenagers in custody after five people were found dead in a shooting at a home in Washington state, police said

A 15-year-old was arrested Monday after five people were found dead in a “gun-related incident” at a home in Fall City, Washington, police officials said.

According to the King County Sheriff’s Office, two adults and three of their children were found dead after officers responded to 911 calls for a “disturbance involving shots fired” early Monday.

The victims were Mark and Sarah Humiston and their three children, and the suspect is their 15-year-old son, CNN affiliate KING reported.

Mark was an electrical engineer and Sarah was a registered nurse, KING5 reported. The children killed were “young teenagers,” Mike Mellis, a deputy and spokesman for the sheriff’s office, said in a news conference Monday.

Another child – a girl – was injured and taken to Harborview Medical Center in Seattle. Her condition was “satisfactory” as of Tuesday, a hospital spokesman told CNN.

“It appears that this is a family incident. This is clearly a domestic violence incident involving not only a young man who is now in significant trouble, but also firearms. Young men and guns,” Mellis told reporters Monday.

According to the Gun Violence Archive, which like CNN defines a mass shooting as one in which four or more people are injured or killed, not including the shooter, there have been at least 427 mass shootings in the United States this year. According to the U.S. Centers for Disease Control and Prevention, gun violence is the leading cause of death among minors in the United States. According to the archive, over 1,100 children and young people died in mass shootings this year alone.

The deaths in Washington state were “committed by firearms” and “there was no significant confrontation” with the suspect when he was arrested, Mellis said.

According to his public defender, the suspect waived his appearance at his first hearing in juvenile court on Tuesday.

Prosecutors have not formally charged him because the case has not yet been presented to them by law enforcement, according to Casey McNerthney, a spokesman for the King County District Attorney’s Office.

In a statement, the teen’s attorneys, Amy Parker and Molly Campera, described their client as a “15-year-old boy who enjoys mountain biking and fishing and has no criminal record.”

“Again, the law requires our client to be presumed innocent of these allegations, and we are grateful for a trial that requires proof and proof before reaching a verdict,” the attorneys said.

A neighbor said she was “completely shocked” when she learned of the deaths.

“I keep bursting into tears,” neighbor Lynne Trowern told KING5. “That’s why I have to go to my daughter’s house because I can’t be here alone. I keep seeing the children’s faces.”