The parents who were gunned down, along with three of their children, inside the family’s $2 million Washington state mansion on Monday have been identified.

Mark Humiston, 42, his wife Sarah, and three of their four teenage children were found shot to death inside the tony home in Fall City — a suburb of Seattle — around 5 a.m. on Monday, King 5 reported.

The couple’s 15-year-old son has been accused of carrying out the carnage. The alleged killer’s teen sister was also targeted in the attack, but survived despite being shot twice.

She was taken to Harborview Medical Center in Seattle after receiving medical aid from a neighbor

Humiston, a Texas native, is a longtime software engineer at Hargis Engineers in Seattle, according to his LinkedIn.

“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,” Hargis Engineers said in the statement to King 5.

“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.”

Humiston’s wife, according to the local news outlet, was a registered nurse. But it’s unclear if she was still practicing as her nursing license expired in 2022.

Authorities have not revealed the identities and ages of the child victims, though they are believed to be teenagers, with the eldest around age 15, neighbors told FOX13.

Deputies responded to the Lake Alice Road home — a stunning waterfront property — just before 5 a.m. on Monday after receiving multiple 911 calls of a “disturbance with gunfire” and found the lifeless bodies of the two parents and their three children, according to King County Sheriff spokesperson Mike Mellis. 

At least some of the 911 calls that alerted deputies to the shooting came from victims who were inside the home and hiding in the bathroom, KIRO 7 reported.

“They shot the other family members, I believe there is five total, not including the RP (reporting party) who’s hiding in the bathroom,” one dispatcher said during a call, according to FOX13.

Mellis explained the shooting appeared to be a “domestic violence” incident involving a “young man who’s in significant trouble, and involves firearms.” 

“Once bodies were discovered, clearly we understand that this is a hugely significant crime scene,” Mellis explained.

Deputies immediately arrested the juvenile after arriving at the family home.

Prosecutors asked the court to charge the teen with five counts of first-degree murder and one count of first-degree attempted murder on Tuesday, the King County Prosecuting Attorney’s Office said.

The teen waived his presence during his would-be first court appearance on his attorney’s advice, Amy Park and Molly Campera, lawyers representing the 15-year-old, said in court.

“Regarding probable cause, we have received a 1-page document that outlines the allegations in this case. However, given the limited information we have and the short amount of time to investigate the case prior to this hearing, we are deferring to the court regarding probable cause,” the attorneys said.

“Finally, regarding release, 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.”

The Huminstons purchased their ritzy three-bedroom, four-bathroom mansion in Fall City — which has some of the most expensive homes in America — in 2019.

A suburb of Seattle, Fall City has a median home listing of $1.5 million.

Mellis described the city of about 2,000 as a “pretty nice area, low crime rate in general.”

“I’m just in total shock,” neighbor Lynne Trowern told KING-TV. 

“I keep bursting into tears. That is why I have to go to my daughter’s house because I can’t be here on my own. I just keep seeing the faces of the children.”

The parents supposedly kept to themselves, but the children were friendly and were known to help neighbors out with home projects, neighbors added.

“So polite. Homeschooled. It’s unfathomable what’s happened,” a former neighbor, Cameron, remembered of the kids.

The nearby Snoqualmie Valley School District confirmed that at least two of the victims were still “school-age,” though none of them attended the district schools.

The teen remains booked at King County Juvenile Detention and is barred from contacting the surviving member of his immediate family, prosecutors said.