Police convention?

On 237 West, just before 101, I was passed by about ten police cars in groups of two and three, mostly canine units. At first I assumed it was some sort of serious problem... And then I noticed the cars were from different places, and not ones I already knew. Redding, San Benito and Arroyo Grande were the ones I saw and remembered, plus a lone CHP car, possibly unrelated to the rest of them.

Is there a police convention in town or something?