The woman crawled nearly 100 yards to get to the road, where she had some chance of being seen by people.
When the four delivery workers found the woman in the middle of the road, she was covered in so much blood that they couldn't tell the color of her hair.
Whoever had done this to her, authorities said later, had stabbed the 19-year-old repeatedly, then thrown her out of a car near a remote, hilly road north of San Jose, leaving her for dead.
But she wasn't.
And in the two hours between when she was found and her death Monday morning, she managed to give investigators evidence that could send those suspected of killing her to prison for the rest of their lives.
"Her internal fortitude, to stay alive and to fight, is pretty remarkable," Alameda County Sheriff's Office Sgt. Ray Kelly told the San Francisco Chronicle. "This young woman clung to life when she was left for dead and was able to live for another couple hours and get us that information. Ultimately that led us to these arrests."
Authorities planned to release more details about the case, the sheriff's office said in a news release, including the name of the victim and charges for the suspects, who have yet to be identified.
The woman had crawled nearly 100 yards - the length of a football field - to get to the road, where she had some chance of being seen by people in passing cars. Authorities determined the distance by measuring a trail of drying blood.
"You could tell it was so bad to where you just had to give her comfort," Richard Loadholt, one of the UPS employees who had been riding with three other men on Tesla Road, told Sacramento Fox affiliate KTXL. Initially, he said he and his workmates thought she was missing an arm. "She fought like a soldier. Like a warrior."
The hilly, winding road where she was found is a popular alternative to Interstate 580 for people traveling between Livermore and Tracy, according to Bay-area news station KRON. It was also virtually deserted in the predawn hours of Monday.
About 2 a.m., the UPS workers sent another driver to an area where there was better cellphone reception to relay information to authorities.
When they got there, they decided the best option was to airlift the dying woman to a hospital with an advanced trauma center. But as first responders tried to save her, investigators asked her questions. The most important one: Who did this?
"I've been around a long time, and I can only think of two to three times that I'm aware of in our agency that we've been able to get a dying declaration like that," Kelly said.
In the legal world, a dying declaration is a statement made by someone who believes they will be dead soon. It's an exception to the legal rule forbidding hearsay in court testimony, and it can hold tremendous sway in a case.
In this one, it led to arrests just a few hours after the teen was declared dead.
Around 10 a.m. Monday, the two suspects were arrested at a home in Modesto, about an hour from where the stabbed woman had been found.
"We were able to act on the information from our victim," Kelly said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)