A lightning strike which scored a direct hit on a gas tank triggered a huge explosion of "pulsating orange" to fill the sky near the British city of Oxford.
Posts on social media showed a large and ominous-looking fireball rising from the horizon, and confusion from people trying to work out what had happened.
Mystery shrouded the explosion until energy firm Severn Trent Green Power moved to confirm a lightning bolt had struck a gas tank during a storm.
Emergency services attended the scene, but early reports suggest no one was injured.
Severn Trent Green Power confirmed that biogas from a container had ignited at its Cassington AD Facility, near Oxford airport, at about 7.20pm.
Jack Frowde, who works at Oxford University, told the BBC he heard a deafening sound and saw a "pulsating orange" light in the distance.
"I was sitting in my kitchen when the whole room lit up with a brilliant white light, then followed by a huge crack which sounded like really heavy thunder," Frowde said.
"I looked out of the kitchen window and it was as if the sky was pulsating orange.
"I ran to the back to capture the orange glow as it faded after about 20 seconds."
Oxfordshire was among dozens of locations in the UK put under a yellow weather warning for thunderstorms by the Met Office.
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