"They overcame every typical little kid fear. The woods, and the dark," the trooper said.
Two four-year-old twins managed to save themselves after their father was killed in a car crash.
Rosaline and Aurora were travelling with their dad Corey Simmons in Whidbey Island, Washington on Friday evening when his car veered off the road, plummeting down a steep embankment and smashing into a number of trees.
After realizing their dad wasn't answering, the sisters managed to free themselves, climbing out through a broken window and scrambling 200ft back up the embankment to the road to look for help.
Luckily a passing Good Samaritan spotted them, picked them up and drove them to safety, before calling 911.
The body of 47-year-old Simmons was subsequently discovered in his car, having suffered a fatal head wound.
State police troopers said he was not wearing his seat-belt; thankfully he had strapped his daughters into their car seats.
"They were just so, so smart to do something like that," Simmons' stepdaughter Rebecah Crider told King 5 News of the girls' astonishing trek. "The hill is very steep, it's hard for an adult to go up and down it."
When the girls were discovered they were both missing their shoes. Yet the only physical injuries they suffered was a bump on Rosaline's forehead, and scratches on Aurora's arm.
The Good Samaritan who spotted the girls told troopers she hadn't see them in her headlights; she had just luckily caught a glimpse of them as she passed.
After turning around to go back and pick them up, she told police, the first thing they said was "My daddy, my daddy, my daddy."
She did not want her name published; but the family are desperate to meet her to thank her for saving the girls' lives.
"We are so incredibly thankful, and we are desperately looking for who she is, her name," Rebecah said. "We would love to personally meet her and thank her.”
"She really saved the twins lives... who knows what would have happened."
Rebecah said her stepfather was very familiar with the route, and couldn't explain what might have caused the crash.
"Corey drove up and down that road every day for about five years," she told the Seattle Times. "I don't know what happened."
Trooper Heather Axtman, who is investigation the crash, was equally stumped by the cause; however she was in no doubt the children's bravery prevented the accident being much worse.
"It's one of the truly saddest stories, but so heroic at the exact same time," she said. "Had those little girls not had the sense of awareness they showed, we would have a missing family. They overcame every typical little kid fear. The woods, and the dark."
A GoFundMe to help the family has already raised more than $6,000.