UPDATED: 11:25 a.m.
These cars, most of them Honda Accords, were located outside of places like the Edge Fitness gym and the Wegmans in the shopping plazas along Easton Road, according to Warrington Police Chief Dan Friel.
Another theft was two miles away at the Doylestown Wellness Center parking lot. Another took place outside of the T-Mobile store on Main Street.
"A lot of these thieves, what they'll do is they'll have a lookout. And they'll watch and pull into crowded areas and parking lots. And they can just slide under. And all they need is a hacksaw and they'll just saw it off," Friel said.
The thefts are happening in the afternoon or evening hours, according to the chief.
It can happen really fast, says Ron Williams with Bob's Auto Repair.
"We actually had one customer that was in a store for only 25 minutes. Came out and it was gone off of his car," he said.
Williams says the bad guys sell the converters to junk yards that then take the valuable metals out of them.
"Platinum and palladium combined, which is a very high precious metal," he said.
They make a few hundred bucks a pop, while the innocent victim has to pay thousands for repairs.
The catalytic converter is usually out of sight for most people, but Williams says if it's gone, you'll be able to hear it.
"You'll start the car up and will notice the car sounding very loud," he said. "Not a normal sound."
Even though most of the affected cars are Honda Accords, police say other makes and models may be targeted as well.
Police are urging drivers to park in spots near security cameras or where a lot of people are walking around, if possible.
Friel says police could use extra eyes and ears.
"We're asking for the public's help as well," he said. "If you see somebody hovering around, walking around, looking into vehicles just call the police."