11-year-old girl 'only survivor' of shooting where software engineer, wife and children were 'killed by 15-year-old son'

Five people believed to be from the same family have passed away following a shooting in Seattle with a 15-year-old having been taken into custody, authorities say.

On Monday (October 21), police were called to a property in Fall City, Washington over reports of a 'disturbance with gunfire at a residential house'.

When police arrived at the property, they discovered two adults and three teenagers passed away and another - reported as being aged 11 - with injuries on 'at least two parts of their body'.

The injured child was immediately rushed to hospital and the King County Sheriff’s Office told NPR that those involved all appeared to be from the same family.

A 15-year-old was booked into King County's juvenile jail later that same day.

The two adults who've passed away have since been named as Hargis Engineers software engineer, Mark Humiston, and his wife Sarah.

King County Sheriff Deputy Mike Mellis told reporters: "It does appear to be that this is a family incident. Clearly, a domestic violence incident that involves not only a young man who’s now in significant trouble, it involves firearms. A young man and firearm.

"What had happened here this morning had essentially concluded before the 911 call was made or before deputies arrived."

Police were called to the property on Monday (FOX 13 Seattle)

Prosecutor John Castleton is reported as having asked the judge to find probable cause to hold the suspect in jail for five counts of first-degree murder and one count of first-degree attempted murder.

Attorneys Molly Campera and Amy Parker from the King County Department of Public Defense argued they'd only received one page of allegations against the teen and that his name should not be publicly released.

The prosecution argued that the teenager is a 'threat to community safety' and the defense said in a statement: "We want the court to know that our client is a 15-year-old boy who enjoys mountain biking and fishing and has no criminal history.

"Again, the law says our client is presumed innocent of these charges, and we are grateful for a judicial process that requires proof and evidence before there is a judgment."

It's reported the teenager will be held in custody until he's charged.

Police state they've never had any calls made in relation to the family's house before and the suspect has no criminal record.

The two adults have been named as Mark and Sarah Humiston (Facebook/ Mark Humiston)

King County Prosecuting Attorney's Office official Casey Mcnerthney told FOX 13 Seattle: "That's unusual to see these kinds of allegations with no previous contact with the prosecutor's office. But that's what we have here."

Family and friends of those who passed away are reported as being set to gather at Fall City United Methodist Church to commemorate them later today.

Hargis Engineers told the Post in a statement to King 5: "We are blindsided and saddened by the tragic events that have led to the loss of a respected colleague, mentor, and friend, as well as the loss of immediate family members.

"Mark’s leadership and vision were integral within our firm, and he will be greatly missed. Our thoughts are with his surviving family, friends, and colleagues during this difficult time."

The 15-year-old suspect is currently expected to next appear in court on Friday.

UNILAD has contacted King County Sheriff’s Office for comment.

If you have experienced a bereavement and would like to speak with someone in confidence, contact The Compassionate Friends on (877) 969-0010.