Yonkers police say they're seeing a big increase in catalytic converter thefts.

Police Commissioner John Mueller tells News 12 that catalytic converters, which are made of valuable metals, can be stolen in under a minute.

Some patterns police have picked up on are the thieves coming out at night and using paper license plates (often from other states) - and they double-park in the street with music blasting so that no one can hear the metal sawing noises.

"The offenders we're seeing have extensive criminal histories...violent criminal histories. So, we're not asking the public to intervene when it's happening. We're asking to call us with the best information we have: description of the vehicle, description of occupants...if they can get a paper plate, that would be helpful too. And we'll get the cops there as quickly as possible," say Mueller.

Mueller says they have more police patrols in the areas where they are seeing the most cases.