Summer locker clean out?

I'm in high school and today is the first day of summer. However, my best friend forgot her bag at my house so on the last day of school I brought it and left it in my locker. She forgot to get it and now all the doors to the school are locked so I cant get in. And this is really important because she had a water bottle of alcohol in it an if its found I'm going to be in so much trouble and it isn't even mine! So my question is when do the janitors usually come in and go through all the lockers to throw things away and will they go into the bag? And when would be the most likely time that the school doors would be open? Please help as soon as possible, I'm really stressed out about this.