Did you hear that loud horn early Sunday morning? That's the question being asked throughout the Hudson Valley as people try to figure out what the heck was going on.

On Sunday morning just after 2:30 am, most of the Hudson Valley was fast asleep. But then, a sudden, loud blast riled residents out of their slumber. Most went back to sleep, waking the next morning to wonder if it was just a dream.

Later that morning, Facebook was flooded with reports from people who heard the loud horn throughout the Hudson Valley. Those who dismissed the incident as nothing suddenly realized that it was no dream.

From the ear-witness reports we were able to collect, it appears that the blast was a very loud, vibrating horn. Most people awoke thinking that it was their cellphone. The noise shook homes and rattled windows, with some claiming they felt their beds shake.

It's unclear what the source of the noise was, but many said it sounded as if it was coming from the Hudson River. Train horns are not uncommon along both sides of the river, but this noise seems to have been more than the usual blasts coming from Metro-North or the long-haul shipping trains on the east side of the river.

The best guess is that it was a large ship on the Hudson River. There were reports of fog on Saturday night into Sunday morning, which would explain the loud blasts. If other ships were in the way, or if a large vessel was navigating the bridges in the area, having to fire up the fog horn would be standard procedure.

With leaves now off the trees, noises from the Hudson River can bounce off of the mountains and travel for miles during this time of year. So it makes sense that so many Hudson Valley residents reported hearing the noise.

Were you woken up by the loud blast on Sunday morning? Tell us your theory about the source of the noise on our Facebook page or in the comments section below.

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