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

If it was rats, the only solution would be to just burn the house down with them in it. With squirrels, you probably just have to hire a company that traps wildlife and then get someone to cover up the point of entry.

On a side note, you can buy animal traps on Amazon or at Home Depot, etc. Not sure it would be worth the cost over hiring a professional.