Maybe you can fashion a one way exit with a trap door that does not permit the rats to go back in, only problem will be that they will get in the building, if you use traps you have to use gloves and use peanut butter you can not touch the traps with your hands at all, place the traps unarmed for a few days until they get used to them and then spring the traps after they get familiar with them.
If you place poison you need to again not touch the containers, rats distrust humans and will not touch food that has our scent, I used to get rid of them with antifreeze, now it is forbidden or borrow a few hungry cats.
Some fire departments use a smoke generator to teach kids how to proceed in case of fires in school, you might rent one of those and try to smoke them out.
Good luck catching them
navegator