Mice seem to hold meetings under kitchen appliances. Number one the stove, number two the fridgeifrator. I had a passle of em try to live here rent free a few years ago. Most effective were the old snap traps like Caj recommended. Get the kind with the flat plastic trip designed to look like swiss cheese (complete with holes and yellow color). Fill the holes in the plastic cheese with peanut butter, and wipe it flush. There's no way they can get it out without getting snapped. Push the trap behind appliance close to wall, so pets can't reach. You cannot reuse traps. The mice will smell the blood an realize what happened to one of their buddies. Like mentioned you have to find where there coming in. I think UV light may show up where they congregate outside before entering house.
I had one get in a Canary cage and got so fat on seeds he couldn't get out. I went to feed the bird one day and there was Mr. mouse looking at me through the bars like "what you want??"

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