Squirrels in the attic can sound as if they are fighting right over the bedroom. The problem is fairly common. We get quite a few requests for live traps to catch them in the spring.
Once animals in the house get a nest started or animals in the attic, they are difficult to evict. First, find their entrance into the attic. Then check for other points of egress similar to that one, because once you seal their entrance they will be looking for other ways to get in the attic.
Do not use wimpy measures to seal the access to the attic. I have seen squirrels try to chew some heavy-duty screen-wire (hardware cloth) off the vents on our store some years back. They really, really want to get back in the attic.
Once ready to seal the entrance try to force them out. Loud noise from a portable radio, mothballs, or a pie tin with ammonia placed carefully in the attic will encourage the pests to evacuate.
Do not get yourself in harms way and do not corner an animal. Another good repellant is the sonic pest chaser. One drawback of these electronic devices is that they are very directional. A pest is perfectly happy to be behind a box or around a corner. In addition, the sonic waves are readily absorbed by insulation so their effectiveness is reduced when dealing with burrowing pests.
Once the pests have vacated the attic you can close up the entrance. Remember, the pests will try to re-enter the attic at all costs.
If your pests are not leaving, try trapping them with a live trap. Placement can be in the attic or outside near the entrance to the attic. Bait it with peanut butter and some peanuts or water. When releasing the pest make sure you travel seven or more miles before releasing them.
Traps are available at some city municipalities (at no charge), or you can rent them from renter centers or hardware stores for about $3.00 to $5.00 per day.