A man has been arrested on suspicion of arson with intent to endanger life after a major fire at a gay nightclub near Milton Keynes.
Revellers had been rushed out of Pink Punters in Fenny Stratford in the early hours of Sunday morning as flames spread rapidly through the building.
By the end of the day, crews were still dealing with "small pockets" of flame, its owner Frank McMahon said.
Thames Valley Police confirmed no injuries were reported.
Now, the force has said a 51-year-old man from Milton Keynes has been handcuffed - though gave no further details as to his identity.
Officers have asked the public to refrain from guessing what may have motivated the incident.
"At this time it would be too early to comment on any particular motivation for this incident and we would respectfully ask for people not to speculate," said Ch Supt Emma Baillie, commander for Milton Keynes.
Molly Firman, from Clophill, was with friends near the cocktail bar when staff suddenly began shouting for everyone to leave.
"Out of nowhere all staff and security were screaming, 'you need to get out now'," she said.
Revellers had been rushed out of Pink Punters in Fenny Stratford in the early hours of Sunday morning
"It just didn't seem real in the moment," she said. "Am I dreaming this? Is it actually happening? Before you knew it, it was just intense."
Ms Firman recalled how the flames grew rapidly once they took hold.
"It felt like in minutes - it wasn't a small fire - but that fire expanded greatly," she said.
Thousands of people were shepherded out onto the roadside to watch the blaze unfold.
Buckinghamshire Fire and Rescue Service received its first call at 2.09am, with crews dispatched to Watling Street.
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At the height of the incident, 12 fire engines were battling the flames.
Firefighters were expected to remain on site for an extended period to deal with remaining hotspots.
Aaron Harding, who has been a cleaner at the venue for five months, thinks around 100 people work there.
"I'm lost for words," Mr Harding, who was not present that night, told the BBC. "I can't even imagine what the owners are feeling - what they're going through."
Colin Ruggles, 61, who lives across from the club, woke at 3am to smoke filling the air.
"It's horrendous, so many people go to Pinks, so many people work at Pinks," he said.
While owner Mr McMahon added: "Worldwide, nightclub fires have too often resulted in a devastating human toll.
"Tonight, we can all be profoundly thankful that this was not the case here. The building has been lost, but lives were protected, and that matters more than anything."
Ch Supt Baillie confirmed that people inside the venue were moved out "quickly and effectively".
Callum Anderson, the Labour MP for Buckingham and Bletchley said "whoever has been involved in this disgusting incident" should "feel the full force of the law".
"I will be asking my team to liaise closely with the police and with the venue's owners to ensure that all appropriate steps are being taken and that the community is properly supported," he added.