Noises and Loud Bang Woke Us Up

This morning, around 4:30 AM, while everyone was asleep. We were awoke by a few noises coming from upstairs. After waking up because of the noises and feeling a little uncomfortable, we heard a very loud bang and were even more uncomfortable. Not sure exactly where the noises or loud bang came from upstairs, but we built up our courage to go check and see what we could find out. We found nothing, out of place and no cause for the loud bang.