A three-month investigation into widespread catalytic converter thefts in Southern California culminated Thursday with five arrests and the recovery of an enormous cache of allegedly stolen auto parts, according to KTLA.

Law enforcement agencies executed several search warrants across Los Angeles and Orange counties, uncovering roughly 2,400 catalytic converters with an estimated value of $4.3 million. Images released after the raids show converters packed into large containers and stacked throughout a warehouse allegedly connected to the operation.

Investigators believe the suspects were part of a broader system for handling stolen converters rather than simply carrying out individual thefts. Authorities say the investigation connected thefts reported across several northern Orange County communities to an organized operation that collected, stripped, transferred and purchased the stolen equipment.

KTLA writes that the searches also turned up more than $105,000 in cash, two firearms that authorities said were not registered and several boxes containing precious metals. Catalytic converters are attractive to thieves because they contain valuable metals that can be extracted and resold.

The operation brought together several agencies, including the Orange and Los Angeles county sheriff’s departments, California DMV investigators, state insurance investigators and the Orange County District Attorney’s Office. Authorities said the scale of the seizure was the product of months of coordinated investigative work.

Following the arrests, officials encouraged vehicle owners to make their cars harder targets by parking in garages or well-lit locations when possible. They also recommended catalytic converter protection devices and having identifying information etched onto vulnerable vehicle components to make stolen parts more difficult to resell.