Many years ago, I was cleaning my apartment while talking with my friend on the phone. I was putting something away in the linen closet and at the same time I closed the door, what sounded like a gun shot happened. Thinking it was something I had done with the door, I tried to recreate the sound, nope. I said to my friend, "Wow, that was interesting, I think someone just got shot." However, since I lived in a pretty quiet apt building I didn't think much of it.
Ten minutes later, there was a knock at my door, I opened it and it was the guy from next door, asking me if I was okay, and if anyone else was in the apartment. Being a wise single woman living in the city, I became very cautious and didn't answer his question, and I had my door slightly cracked, preparing to shut it. He went on to tell me that he was cleaning his gun and it went off, and he wanted to make sure everyone was okay. I told him I was, thanked him, then closed the door (and locked it.)
I went to the room that shared the wall and sure enough, there was a hole in the wall and one in the wall across the room. I taped some paper over it and went to bed. The next morning I called the apartment super and they came to fix it a few weeks later. The guys next door were evicted, but only after my friend (and upstairs neighbor) called the manager's office again to push the issue. (I had asked to have them moved bc I didn't feel comfortable living next door to them.)