Charity runners taking part in a 10km fun run at the weekend were left exhausted after being sent on an unscheduled two-mile detour. The blunder was believed to have been caused by a race marshal taking a toilet break during the event, missing 300 runners who should have been directed at a junction point. Instead they continued past the unmanned marshall point and had to run for an extra three kilometres while the other 900 competitors followed the correct route. Scroll down for video . Blunder: Charity runners taking part in yesterday's Bournemouth Bay 10K Run (pictured) were left exhausted after being sent on an unscheduled two-mile detour . The bizarre gaffe happened during yesterday's Bournemouth Bay Run and today the organisers - Bournemouth Borough Council - appealed for those who were affected by the mix-up to contact them for a 'gesture of goodwill.' A local authority spokesman said that it was investigating what happened to the marshal who should have directed runners at a turning point. It was reported that some runners were 'in tears' while one described the event's organisation as 'shambolic'. Hayley James, who is four months pregnant and from Poole, said: 'To have a race of that scale with only one marshal on a point is inexcusable. 'We saw loads of people walking at the end, some were in tears, I felt so sorry for them - I felt like crying at the 10km mark.' Andy Isaac, from Bournemouth, said the event was 'mayhem' with one point where an elderly woman managed to drive onto the route and was flashing her lights at oncoming runners. A map shows where up to 300 runners continued along the coastal path after a marshal who was meant to direct them on to a turn went to the toilet . Reaction: Two people vent their frustration at the Bournemouth Bay Run on Twitter yesterday . It also emerged that water stations ran out of supplies during the race, forcing some runners to drink from half-empty bottles that had been left on the ground as they battled against dehydration. Commenting on the Daily Echo website, one runner said: “We had a bottle of water at the three mile station, but at the six mile point they had totally ran out, so nothing. Jon Weaver, head of resort marketing and events at the council, said: 'Unfortunately there was some confusion with marshalling arrangements at one point, but it was a critical point. We apologise unreservedly to those front runners. 'In 33 years of running... this is the first time this has happened and as part of our debrief we will be analysing the arrangements carefully... to learn for 2016. 'We understand runners have trained for a long time for the event and it's hard for them and we do empathise with how they are feeling.' It was hoped that the event would have raised more than £70,000 for the British Heart Foundation. Some racers took to Twitter to vent their frustration over the blunder. Rob Kelly wrote: Really disappointed in the #BournemouthBayRun 10k that ended up 13k very poor show bad marshalling #wontbeback.' AndKim Kelly replied: 'Totally agree and never got to do a 5k as they were 45mins behind schedule :(((.'
Up to 300 runners in yesterday's Bournemouth Bay Run sent wrong way . Some of the racers were said to be 'in tears' after the two-mile detour . Organisation slammed as 'shambolic' as there was also water shortage .