The grief comes in waves - the tears too.

It’s hard to know when either will hit Marcus Mason, the uncle of Sophia, 5, and Noah, 7. Their 19-year-old brother is accused of stabbing them to death Monday in Colorado Springs.

“We’re living the worst nightmare,” Mason said. “The worst nightmare. But I’ve been wanting to just wake up, snap out of it. This can’t be real.”

The kids’ mother, Melissa Mason Murphy, is Mason’s sister.

Mason agreed to speak to 9NEWS because he wanted to share who the children were and clear up some information about Malik Murphy, the 19-year-old suspected of killing his siblings.

“Sophia and Noah,” he said, “I know everybody says, ‘our kids are so sweet.’ These kids were really sweet, they were really sweet kids. I just don't understand. I don't understand.”

Police in Colorado Springs said early Monday morning that the kids’ older brother stabbed the two. According to an arrest affidavit, Murphy admitted to the attacks. Murphy also told them he had “homicidal ideations” and wanted to kill his family to be alone in the home.

“That’s what people need to understand,” Mason said, “it wasn’t like there was ever a warning that he would actually do it. Or do anything to harm people.”

“[Malik] never raises his voice,” Mason continued. “He was caring to his siblings, he wasn't a mean brother to them. He really wasn't. He helped out and even that evening they were playing together in the yard, with a football, throwing the football around. He's playing with his siblings.”

Arrest documents indicate Murphy’s father Jefferson ‘Vinnie’ Murphy came down to the basement after he heard the screams. His 19-year-old son told police he stabbed his father in the neck. Jefferson Murphy was released from the hospital that day.

“I’m just so thankful,” Mason said. “Sophia saved the day. She saved the day, she ruined his plan by screaming. If it wasn't for her, Vinnie wouldn't have woken up. That was a strong little girl.”

Sophia was 5. She was friendly and loved meeting new people. She loved Barbie dolls and “My Little Pony.”

“Sophia was the sweetest little girl,” Mason said. “She always wanted to help with chores, she’d help with her mom doing laundry, cleaning the bathroom. She would get mad if her mom wouldn’t let her clean the bathroom.”

Noah was 7. He was very social and would talk to anybody.

“Noah can be a little ornery, you know, like a little boy would be,” Mason said. “He would maybe do some stuff, tease you, annoy you a little bit, he was a super big imagination, he would play by himself with his toys. He could just totally entertain himself, he didn’t need people to play with.”

Mason said his nephew, Malik, made a decision Monday night not to be a part of the family.

“I know a lot of people want to know why - I honestly don't even want to know why. It isn't going to change anything,” he said.

Mason said Malik Murphy struggled with depression, but the family was working through that. They had been and were getting him help.

“They were seeking help for him and trying to do all they could,” Mason said. “They were doing stuff, sending them to professionals and he was staying in places, getting help. So it’s a balance of when you have a child, you love them, yes, he was at the age he needed to get out. There are people saying that. And that was the plan: to get him a job, to get his money together, get out.”

But Monday something happened. Something that doesn’t make sense to the entire family.

“I just ask people keep praying for us, thinking about us, this is definitely the hardest thing I can ever imagine,” Mason said.

The family wants to thank the community for their support. Here’s a place you can still help them.

The funeral for Sophia and Noah is Monday at Mountain Springs Church in Colorado Springs. Mason said the community is welcome.