The CHP is pursuing leads it hopes will help identify a big rig involved in a freak accident that resulted in the death of a Mendocino County woman whose car was struck with parts from an exploding brake assembly Wednesday.

The 23-year-old victim, Willits resident Sugey Garcia, died when the impact of the flying debris caused her to drive off the side of Highway 101 and over a steep embankment just south of town, authorities said.

The CHP said Thursday the woman was driving northbound near Walker Road just before noon when she came up behind a tractor-trailer rig and her car was suddenly struck by at least one airborne object, initially thought to be scrap material or cargo being hauled by the tractor-trailer in front of her.

Later investigation indicated it more likely was part of a metal brake assembly from a rear trailer that blew apart, CHP Officer Kylar Adams said.

It’s possible the truck driver didn’t even notice, Adams said.

But “the pieces were pretty big,” he said. “We’re talking about football size.”

The resulting impact caused Garcia’s 2014 Subaru Impreza to careen left across the oncoming lanes and over the opposite side of the highway, missing several trees but landing quite a way down the embankment, Adams said.

Garcia was pronounced dead at Ukiah Valley Medical Center, the CHP said. No cause of death has been determined.

A large dog in the back of her car survived, Adams said. He said the animal did not appear to be injured.

There were multiple witnesses to the crash, and, after reinterviewing some of them Thursday, the CHP said it was looking for a white three-axle conventional tractor-trailer, possibly a Volvo, hauling a dark orange or rust-colored trailer similar to the color of a Conex shipping container, Adams said.

The CHP said the truck also likely had wheel or brake drum damage but could have traveled some distance before the driver realized anything was wrong.

“The size of the debris leads us to believe it’s a larger truck, mostly likely a multiple axle vehicle,” Adams said.

A request for information from the public has elicited “good leads, good possibilities,” he said. “....But as of yet, the truck is still MIA, missing.”

Anyone with information about the incident is asked to call the Ukiah Area CHP Dispatch Center at (707) 467-4000.

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.