Car theft is something every owner has to worry about, whether the vehicle is powered by gasoline, electricity, or a combination of both,

But sometimes, rather than stealing an entire car, criminals only go for certain valuable components.

Thieves in San Francisco are reportedly targeting Toyota Prius hybrids--and stealing only their battery packs.

CHECK OUT: Replacing A 2001 Toyota Prius Battery Pack: What It Cost (Jul 2012)

And it's possible those stolen battery packs are being sold on the black market as replacements for packs in high-mileage cars, reports The Verge.

Over the past few weeks, there have been several cases of stolen Prius battery packs in San Francisco.

Thieves apparently smashed the cars' rear windows and lifted the battery packs out from the trunks of the vehicles.

2009 Toyota Prius

2009 Toyota Prius

Since battery packs don't come with identification numbers, there's less risk in stealing them.

It reportedly takes a trained professional about an hour to remove a Prius battery pack--presumably with all safety precautions--but the thieves apparently do it in about 20 minutes.

Presumably these thieves have some knowledge of electrical equipment, as they've been able to disconnect and remove the 120-pound packs without getting electrocuted.

ALSO SEE: Toyota Hybrid Battery Replacement Cost Guide (Aug 2012)

However, they may know a bit less about the mechanics of hybrid cars.

First- and second-generation Prius models are the ones most likely to need replacement battery packs after their warranties have expired (either 8 years/100,000 miles or 10 years/150,000 miles, depending on the state).

These packs can cost up to $3,000 retail, but a rash of Craigslist posts for packs costing $900 to $1,000 has led to suspicions that stolen packs are being passed off as cheaper alternatives to dealership replacements.

2003 Toyota Prius

2003 Toyota Prius

There's just one little problem: The vast majority of stolen packs come from third-generation Prius models, and aren't immediately interchangeable with the packs in older models.

That would seem to throw a wrench into the whole scheme.

This isn't the first reported spate of Prius battery-pack thefts.

MORE: Life After Death: What Happens When Your Prius Battery Dies (Jan 2012)

The New York Police Department recorded 14 incidents of theft between November 2014 and February 2015.

The majority of victim cars were Prius taxis.

Ironically, because of their typically-high mileage, taxis are also among the most likely to need replacement battery packs--black-market or otherwise.

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