About 200 people took part in Manchester's first "flash mob" on Wednesday night.
The flash mob jumped up and down with their umbrellas open
The crowd descended on the city centre's indoor Printworks complex and jumped up and down with their umbrellas open.
The mob's organisers had intended to pull the stunt in the complex's Filmworks cinema, but were foiled by staff.
Almost as soon as the mob had formed, it dispersed, in true "flash mob" style.
The surreal phenomenon originated in New York and has spread across Europe.
Its aim is to arrange sudden gatherings of people at predetermined locations and times and then disperse quickly, leaving onlookers confused.
The Manchester flash mob had been arranged through the flashmob.com website while emails had been sent to participants during the day, telling them to meet at pre-arranged pubs in the city centre.
They were told to bring an umbrella and approach a man in a red shirt drinking a pint of Guinness to be told what to do.
A Filmworks spokesman said: "We were tipped off that they were coming by the police.
"So we pulled the shutters down and made sure we only allowed customers into the building.
Stopped by security
"We were worried it would be a fire hazard."
Organisers then tried to take the "mob" into the Norwegian Blue bar, opposite the cinema, but they were stopped by security guards.
One person who took part said afterwards: "It was brilliant. Four of us travelled into town to take part.
"We'd only just heard about it yesterday and found details on the internet.
"'I've not laughed this much for a long time. It's all a bit of fun as long as no one gets hurt."