My name is Akshath. I have experienced these paranormal activities two times in my life and I would be writing down one of it now and the other one later. (Please bear with my English.)
This must have happened when I was in my schooling days. Being a resident from Mangalore, I visited my uncle's house which was next to the railway tracks. My uncle had bought the house and started living in it.
As I had summer vacations, I wanted to visit and stay in my uncle's house and my relatives were talking about this experience in that house. I was anxious and I decided to stay there for a week.
This activity used to start around 8:00 PM when the power goes of as we used to have these "Load Shedding" to save electricity. In these houses they have an attic with a wooden flooring and my uncle used to store coconuts in the attic. At around 8:30 PM we hear this sound in the attic as if some on would bang with a hammer or an heavy object in a proper series. First it would be three bangs and after few seconds again three bangs. (These sounds seriously increase your heartbeats.)
My two uncles and many more relatives including myself were sleeping under the attic and was waiting eagerly to witness the sound and then it really happened. And when I experienced these, I really got scared as it was not sounding normal. Many relatives had different explanation. Some said it would be the rats or the wooden flooring that expands due to heat and and all that. But trust me, these sounds were like someone was really banging the attic floor. My uncle and I checked the attic the next day but there was nothing except for some coconuts lol... But we both were so scared.
The house was blessed by the priest several times and it had no effect. Finally, I got to know that my uncle, as they are very religious and being Roman Catholics, had asked service from really powerful nuns (powerful means spiritually) and then the sound had stopped. They say that the house was occupied by Hindus who had a "TULSI Katta" in front of the house, a place were Hindus pray early in the morning, which was removed by my uncle and that was the cause. No one ever knew why it was happening but seriously, guys, it was one scary experience.
Sorry, I am writing for the first time so I could not put it in a way that might thrill you. Will try my best next time.
Also as huldufolk pointed out, I guess accidentally you clicked in Iceland instead of India, I guess its a common mistake happens as anywhere in country list, iceland is just above or below India in the list. Kindly request to correct it lest the story gets catalogued in the wrong country.
I sincerely hope that the scenario is under control at your uncle's place. The reason mentioned is highly possible situation as many a times a spirit's chi gets disoriented with relocating some of its object it is being possessive or attached to in their earthly life time.