From what i can tell it's a dream about the rapture it seems to fit the description of what Jesus said it would be like
in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed
In your dream you saw a bright light and heard a loud trumpet while you were talking to people in a room, the fact it fits this verse so keenly is little more than coincidence and I am guessing it happened as if out of nowhere yes? Jesus said that he would come as a thief in the night meaning it will happen in an instant like a flash of lightning and seemingly out of nowhere.
He even said to me himself a few months ago that the rapture is sooner than I think, I was losing hope and having doubts but he himself spoke to me in a dream saying to not give up on the rapture because it is closer than i think.