Glasgow residents took to social media after a loud "apocalyptic-sounding" noise rattled the city early on Monday morning.
At around 2.55am, a number of people reported hearing a sudden "explosion" — with some saying that it "shook" their homes.
The exact cause of the sound is not yet confirmed, but many residents believed the "frightening" noise was thunder.
READ MORE — Glasgow braces for wind as centre of Storm Franklin moves across Scotland
Many people also reported seeing flashes of lightning, perhaps indicating that thunder was indeed the source of the sudden sound.
Data from lightning-tracking website LightningMaps.org appears to confirm that the area around Glasgow experienced lightning overnight.
Taking to Twitter, one person commented: "Anybody in Glasgow hear the loud bangs last night??"
"I can't see one weather map that mentions thunder and lightning but it literally just shook our house outside Glasgow," a second tweeted.
A third wrote: "Oh, as if the wind and torrential rain isnt bad enough, we get apocalyptic-sounding thunder with #StormFranklin too? Hiding under the duvet here in Glasgow now."
Another said: "Was wind and rain not enough? Why you throwing thunder and lightning into the mix Franklin".
"Franklin, Glasgow last night was scary and very wild and the unexpected thunder was icing on cake," agreed a fifth.
"There was one near Glasgow around 2am huge flash of lightening too," stated a sixth in response to a tweet from from another user about thunder on the Isle of Bute overnight.
Meanwhile, on Facebook, one user wrote: "Morning, did anyone else hear the thunderous explosion-like sounds around 3am this morning? It was really frightening."
A second concerned Glasgow resident shared: "Did anyone else get woke up by that noise? Sounded like a bomb going off."
Another said: "Hope you all got a good night sleep. Or did you get woke up at 2.55am this morning with the loudest bang that I've ever heard!"
