Inspect the exterior of the home, including the roof and all vents, to find out how the animals are getting in. Also inspect inside the attic to identify animal and damage.
This process is not simple, and it varies considerably based on animal type and situation. You might use an exclusion door, or a cage trap, or removal by hand.
The job is not complete until you solve the source of the problem. Seal shut the entry holes, with professional grade repairs, or else the problem will happen again.
In addition to repairing chewed electrical wires and damaged duct work, you might want to remove the animal feces, maybe the insulation, and decontaminate.