An inky blackness descended on the town; a blackness of depredation as much as a blackness of the night.
The spots of rain quickly became a storm. Thunder and lightning and torrential rain blasted the town for three hours without respite and water poured down the moors to swell the reservoir until, with a crack which dimmed the thunder, the embankment gave way.
The water level dropped in moments by up to 40ft as tons of earth, stone and sand were swept along by the swirling torrent down the small overflow stream towards the winding network of alleyways which started close what is now the former Co-op bakery building in Borough Road. The deluge struck with devastating force, ripping apart culverts, roads and houses. The horror in those cellars is impossible to imagine. One moment families were fast asleep in one, perhaps, two rooms, fitfully gathering some strength for the toils of the new day; the next moment they were fighting for their lives as floodwater blasted through the street gratings and doors.
There was no local newspaper to tell the story 150 years ago and it was left to Edward Gregson, the town's only printer, to publish an account of the tragedy which he headlined: "Most Alarming and Dreadful Accident in Over Darwen."
He began thus: "We have to record one of the most alarming and melancholy occurrences that has ever taken place in this part of the country by the bursting of a water lodge, situated to the west part of the town, which was attended by most fearful consequences, there being no less than 12 human beings hurried into Eternity with scarcely a moment's notice, the greater part of them being drowned whilst asleep."
A house and shop owned by John Turner was quickly flooded to a depth of five feet. His wife ran downstairs to investigate the roar in the darkness, dropped the baby she was carrying but just managed to grab it by a leg before it was swept away. The first and second floors of the Cooper family's home collapsed on one side, but they managed to scramble to the safety of the hill behind by breaking a back window. In a narrow passage called Lumb Street the water crashed through the front doors of two houses and Ellen Townley and Mary Day held three children above their heads for an hour until they were rescued. Next door John Townley, his wife and children were hauled to safety by John and Ralph Shorrock who had seen blood-stained hands clawing through a broken window. One little boy who had a miraculous escape was carried by the surging tide from Water Street nearly 200 yards to the Angel Inn in Market Street - the old Burton's building is on the site - before the lad was snatched to safety by shoemaker John Hindle just as he was about to be whirled into the underground culvert.
There were many tales of heroism from that night. Emergency services? Hardly, in those days. Everyone weighed in as Darren folk, young and old, showed time and again that although they might not have two farthings to rub together they would all pull together in a crisis.
Sadly, for some, only divine providence would have saved them.
Three linked cellars under the Bury Street house of shoemaker Christopher Bibby were occupied by the Knowles and Lassey families and a young man called Haworth. The only entrance was though the front door and the water poured in.
Only John Lassey, 20, survived. Although water rose to within four inches of the ceiling he managed to keep his face above it by clinging to the chimney-piece. Mary Shaw and two of her five children also died in a Bury Street cellar. In another cellar in Church Street widowed Alice Nixon managed to save only one of her two children. Next to the Black Bull in Market Street a cellar under a tailor's shop was occupied by Henry Bury, a fishmonger and fruiterer, his wife and three children.
When the flood hit he and his wife managed to drag two of their children to a higher part of the cellar and hold them high until being rescued. They could do nothing for their baby.
The 12th victim was Ellen Walsh, on old woman who also lived in a Market Street cellar under a butcher's.
As Edward Gregson reported: "To describe the horrors of the scene when the storm was at it height, the thunder rolling overhead, the lightning flashing incessantly, the flood pouring from above and rushing through the streets, and the drowning people screaming in their dying agony for help, would be impossible."
It must have seemed like the end of the world.
For some of them it was.
Research by the late Norman Bentley