any ideas?

I went to one of the local pet stores a few days ago, they had some beautiful golden and silver/blue colored mice so I grabbed a few to add to a colony. I keep a little critter cage in my car so I put them in there and off we went. We were about 10 min away from the pet store when one of my roommates noticed that the mice were wet. I told them that one probably peed on the others and not to worry. But they looked soaked a few min later when she asked me again. Then one laid down and died, then another did the same thing, I had enough time to toss the two dead over a fence into a pasture and then the third dropped dead.
Any ideas on what could've caused that? :shrugs:
Thanks

Were they in direct sunlight? When is warm that day (specficially in your car)?

Could be any number of things. For all you know those mice could have been sick to begin with.

they were not in direct sunlight, but this is texas and my car is black so they may've gotten a temp shock when i put them in the car. they didnt have trouble for awhile, the AC was going and it was cool by the time we noticed that they were wet.