Anyone hear a loud sound in Bemidji?

My wife and I were woken up at5am this morning from a very loud sound that seemed to be coming from the south. If I had to describe it, it sounded like a very large volume of pressurized gas escaping very quickly. Anyone else hear it?

No but we're NE of town on the other side of the lake. Wonder what it was?

No I did not hear anything. Might have been something to do with the pipeline??

That's kind of what I was thinking. I know they've been pressure testing the new pipe lately. My dad has actually called 911 for a similar sound not to long ago, and that's what they said it was.