The sister of the Washington man accused in the "astonishing" slayings of their two younger brothers said the family is "still in shock" over their sudden, tragic murders.
Seth South, 23, allegedly killed his teen siblings at their home near Poulsbo, Washington Oct. 9, according to the Kitsap County Sheriff's Office.
Their older sister, Shyanne South, 21, identified the victims as 17-year-old Scotty and 16-year-old Sebastian South.
"My family and I are still in shock, we're trying to understand what led up to this and where to go moving forward here," Shyanne told PEOPLE in an interview Thursday. "We're trying to understand the emotions that come with grieving."
"Scotty was very family-oriented," the grieving sister recalled of her aspiring park ranger brother. "He just wanted to be around my parents, his siblings and grandparents."
As for Sebastian, who they lovingly nicknamed "Bass," their parents were planning on enrolling him in driver's ed, "and it was looking like within the next six months he would have finally had his own license and been able to drive his friends around," added Shyanne.
Seth triggered last week's investigation when he allegedly called 911 himself to report that one of his brothers slit their own throat, KIRO-TV reported, citing court documents.
While on the phone, dispatch allegedly heard a struggle in the background and stayed on the line until officers arrived and found both siblings dead. Seth allegedly fled the scene before cops got there.
Shyanne said the shocking allegations against her older brother are completely out of character and has left her family with more questions than answers.
"For 23 years of his life, he loved us all so much and he was a very generous person," Shyanne said, according to the outlet. "It's astonishing... up until (last) Wednesday nobody could have ever thought anything."
As the family tries to adjust to their new normal, Shyanne launched a GoFundMe to help offset funeral costs and give them time to cope.
"In one incomprehensible day, our family of seven became four. We are heartbroken, confused, and the financial burden of this tragedy is devastating. I can't believe I'm writing this message, and I can't believe I'm asking for help, but we are shattered," she wrote, according to the fundraiser description.
"We've not only lost Scotty and Bass, but in a way, we've lost Seth too," she continued.
"I'm not sure we will ever fully understand what happened on Oct 9th. Seth saw Scotty and Bass every day; he celebrated family moments and supported everyone. Up until then, Seth's love for his family was undeniable."
Seth has been charged with two counts of murder and one count of assault, according to authorities.
It's unclear if he entered a plea or retained an attorney to comment on his behalf.
A motive remains under investigation.
