I entered the city on hwy 7 from the south. After passing the only stop sign in town, I saw a city police car in front of me going the speed limit of 35. I did the same. He pulled off and stopped near a school on the right. I watched him as I continued at 35. Down the road near the change to 45, he started after me with flashing lights on. Told me I had gone through a school zone with its yellow light flashing limit of 20 mph. This was at 11 am. I didn’t go back to see if light was flashing and if his car blocked view of yellow light, but I think it was entrapment of out of town vehicles and he had found a good way to distract motorist with his car. I think this is his normal routine.