The Sheffield Half Marathon has been cancelled "due to a problem with the delivery of water", the organisers said.
The cancellation of the race, which was due to take place today, was announced on the Sheffield Half Marathon Twitter account and Facebook page.
"It is with huge disappointment & regret that we have been forced to cancel this year's race due to a problem with the delivery of water," a post said (sic).
It added: "We would like to express our sincerest apologies to everyone involved in the race who will be affected. We will update you future plans asap".
Just a couple of hours previously, a tweet was posted by the account calling on people to tweet their race day pictures, adding: "Today is the day!"
South Yorkshire Police said that despite the cancellation, a large number of participants have still chosen to run the race.
The force, which was initially present on parts of the marathon route to assist with the road closures to motorists, added: "Working with the organisers, officers attempted to speak to participants who had chosen to run and divert them on to a shorter route to the finish line.
"However, officers have kept their positions and stance with the initial road closures to motorists to protect all the runners and ensure their safety is maintained."
There was an angry response to the announcement of the cancellation on Facebook.
Mel Broadhurst commented underneath the post: "Absolutely disgusting!!! My friends and I have trained for months some raised a lot of money for charity.
"Terrible lack of communication, won't be doing the Sheffield half again!!!! And I will get my money back!!!!!"
Craig Reed wrote: "It'll be the nail in the half's coffin. And are you refunding all of us?"
Adam Broadhead wrote: "That is absolutely shocking organisation. You guys have embarrassed the city."
Adam Stern said: "So disappointing for the runners but I also have to say hats off to the Sheffield communities for their efforts in supplying water unofficially to the runners! Proud to be from Sheffield for that, just a shame the organisation and communication of the race was so shambolic!!"
Jonathan Sutton said: "Oh dear, I imagine you'll struggle to get many entering next year and may even struggle to find corporate sponsors. How the hell can this even happen?"
The Sheffield Marathon Twitter account has since tweeted: "Those who crossed the finish line with their race number will be timed & we'll be providing a list of all finishers & their times".
Margaret Lilley, chair of the race organisers, told the BBC: "We had a problem with the supply of water.
"The company we had asked to supply bowsers for the route did not arrive this morning.
"We have scoured supermarkets around the city, but unfortunately we have not been able to secure enough water for the medical-and-safety officers of the race to say it is safe to go ahead. We therefore took the very reluctant decision to cancel the race."
Ms Lilley added: "Runners had waited half an hour or more to start. When we made the announcement the runners decided that they wanted to race anyway, and all 5,000 of them set off."Suggest a correction