That wreck claimed the life of two young girls, ages 1 and 7, just before 5 p.m. Sunday on I-435 near State Line Road.
"As soon as I moved over to the furthest right-hand lane, I noticed there was a van stopped in the road," Layton Wilson explained.
Just moments later, Wilson and his girlfriend Dakota Chambers saw a semi slam into the back of the van. It was carrying 37-year-old Angelica Hernandez-Valentin and four children. The family said they were coming home from a birthday party.
"There was nothing that I could have done to prepare myself for when I walked around the other side of the van," Wilson said.
He found sisters Teresa and Ruth Vasquez killed, and a 9-year-old boy and his 14-year-old brother injured. Next to them, Hernandez-Valentin was lying on the side of the road.
"I was kind of patting her on the back and just seeing if she would say anything to me or say anything period, but she was just laying face down crying," Wilson said.
Chambers, his girlfriend, held the hand of the 14-year-old boy who was injured. She said the teen kept asking for his family.
It was a crash so horrific, first responders struggled to fight back tears.
"Hug your loved ones," Kansas Highway Patrol Trooper Candice Breshears said, her eyes welling up.
Many stopped to help the family and the truck driver involved in the crash. Wilson said nearly a dozen cars helped the victims or directed traffic. One man even used his belt as a tourniquet to stop the bleeding on the 9-year-old boy's leg.
"I don't think there was really much else we could've done, made anything better, except just to let them know, 'hey, we're here, we're trying, help is on the way, and we're doing what we can for you,'" Wilson said.
The driver of the semi was treated and released from the hospital by Monday afternoon. The wreck is still under investigation.