A 60-year-old Nipomo woman was killed in a freak accident about 4:10 p.m. Wednesday when a piece of heavy equipment fell from a truck-and-trailer rig on Highway 101 onto her car stopped at an offramp, according to a California Highway Patrol report.

The woman, identified by the CHP as Pyong Yun Song, had driven her 2008 Cadillac Escalade down the northbound Willow Road offramp and was stopped behind a 2016 Mazda 6 driven by Eliodora Cardenas, 53, of Glendale.

At the same time, David Edmundson, 62, of Arroyo Grande, was driving a 2014 Peterbilt semitruck towing a lowboy trailer loaded with an excavator northbound on the freeway when his right front tire blew out, the CHP said.

Edmundson lost control of the Peterbilt, which traveled off the east side of the roadway and struck a guardrail, dislodging the excavator — a piece of heavy equipment with a bucket for digging mounted on a boom connected to a rotating cab atop a frame and tracks.

The impact dislodged the excavator, sending it over the side and down on top of the Escalade, killing the driver, the CHP said.

Cardenas’ Mazda was also struck by debris from the impact, but she was uninjured. Edmundson suffered minor injuries.

The accident closed the right lane of Highway 101 and the northbound offramp for about two hours as emergency crews recovered the victim and removed the debris, according to Cal Fire/Santa Barbara County Fire Department.

The CHP is asking anyone who witnessed the crash to contact Officer Mallory and the San Luis Obispo Area CHP office at 805-594-8700.