A "loud bang" in south Liverpool reportedly caused lights to flicker in people's homes and their wifi to cut out.
Shortly before 9pm on Friday night, dozens of people took to social media to ask if others in their area had heard the noise and if they had experienced any problems because of it.
A number of Twitter users in Mossley Hill said that they had lost power in their homes, their internet connections and house alarms were being set off as a result.
Reaching out their followers, user @RainyRain_ said: "Something on Allerton Road.
"Power has gone off, internet lost connection."
Chris Mac also tweeted: "Massive bang in Mossley Hill just now, dead weird.
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"All electricity off and all the house alarms and car alarms going nuts.
Chris Williams added: "Just heard a very big bang in the South Liverpool, Mossley Hill area and all the lights flickered.
"Anyone know what it was."
A number of people also reported seeing firefighters outside the Tesco on Mather Avenue minutes after the incident.
Chris Williams added: "There's a fire engine outside Tesco and looks like they evacuated/ closed the store."
The ECHO contacted Merseyside Fire and Rescue for more information about the incident who confirmed they were in attendance at the store.
Explaining what happened, the fire service said that an electrical substation at the busy supermarket had experienced a fault which may have caused the noise that many residents heard.
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A spokesperson added: "The fault shorted the electric to the store and we are in attendance as a precaution.
"This may have caused the loud bang and brief electrical problems for those living nearby but this should not continue.
"There is no fire at the store and thankfully no one was injured."