Officers were called to the 1600 block of North Placentia Avenue at about 6:20 a.m., according to Sgt. Shane Carringer of the Anaheim Police Department.
When they arrived they saw the man under the car, Carringer said. It appears he was trying to steal the catalytic converter from the car when the jack he was using failed and he was crushed under the weight of the vehicle, Carringer added.
The man's name was not immediately known.
Authorities say catalytic converter thefts are on the rise as thieves seek metals in the car parts they can sell.
"They're filled with precious metals such as platinum, palladium and rhodium. I believe they melt them down and separate the metals and sell them because they're worth more than gold," said David Kilbourne, who runs Foreign Carriage Service in Thousand Oaks.
RELATED | Tips to prevent thieves from stealing your catalytic converter
RELATED | Catalytic converter thefts on the rise in LA, police say. Here's why
The video in the featured media player above is from a previous report.