Redwall warriors

I am in the living room. I hear a sound. My roommates are not home, and so I wonder. Into the kitchen--the sound is coming from a roommate's pantry.

I slowly open the door. On the first shelf--a good two and a half feet off the ground--two mice, duking it out for all they are worth over her prepackaged goodies.

They looked at me in shock. I looked back. I made some half-coherent threat. They scampered away (jumped down?).

Mice have invaded our kitchen. I scrubbed every surface I could at the end of the day, put all the food away, and took out the trash. The exterminator's already been here.

Any suggestions for how to fix this problem?