Exterminators in the N.O. area - large rodents in the attic (3-month update: Rats gone!)

Look around the outside of your house at the soffits and see if you can find an entry point or better yet see one go in/out. After you find the entry point set some traps at those points. If you use a rat trap make sure to drill a hole in it, attach a rope, and tie it off somewhere. Don't want one dragging it into the house and dying. For a squirrel I'd use a small live trap with bait in it. Trail cams have also gotten really cheap and you can set one of those up to try and get a pic of what you're dealing with.