Talk to the cat telekinectly tell him/her to open the door and keep the door unlocked forever. :3

As you're probably not gonna be able to make a copy of the keys, you should really just contact the school and say there's a life at stake.

Call a housebreaker

check if there were any opened windows / doors and throw in opened cat food ^^

Call a locksmith? Is it a rental house? Maybe the corporation has a spare key?

Don't worry about it, the cats will resort to cannibalism and at least one should survive.

Contact School or Police.

Train monkey to get the keys

Call Chuck Norris!

Let the cats die... ^^

well,there are four options:

1. Inform your friends,they will have a spare key somewhere or they will come and open the door(better than dead kittens :3)

2. contact the school or a school keeper and say you have left something very important in a locker

3. Just let the cats die(they wont really die,they will just be starving to death when ur friends come)

4. crash bash into the house,break a window,try to pick the lock or something

other wise,you IZ screwed