An empty, upright, open 5 gallon bucket is an effective mouse trap. Put something beside it so they can get up to the rim, and make sure the inside's empty and smooth so they can't get out. After the first one falls in and dies of thirst, others will follow to investigate the smell. If you want to bait it initially a bit of peanut butter near the rim for smell should be enough.

We make a habit of leaving water and garden buckets upside down, outside, so we won't discover dead mice in them when we use them.