“I was then asked to get out of the ambulance because somebody else was in a worse condition and needed priority.”The victims were taken to Rotherham Hospital, where some were kept overnight. Mr Allison was told some reactions were severe because they had never taken drugs and their bodies did not know how to react.Mr Cook is also understood to have fallen victim to the prank and was taken to hospital.He told a friend it was “terrifying” and he thought he was having a heart attack.Julian Evan-Hart, 57, editor of Treasure Hunting magazine, who was not at the event but has spoken to several attendees, said: “They’re all okay but a bit shallow headed because if you’re not used to that kind of thing, well it blew them apart basically.“I think everyone is very much thinking this was a bit of tongue-in-cheek joke where the wheels came off.“It does broadens one’s mind – if you’re going to mess around like this, you’ve got to be so careful. “I’m certain that this lady didn’t intend this to happen, it was going to be a close-circuit cake shared amongst friends but then everyone helped themselves from what I can gather.” Metal detectorists attending the Coil to the Soil rally in Yorkshire had anticipated a gentle four days scanning 400 acres of land for treasure.But the event descended into chaos when a birthday cake laced with cannabis oil was unwittingly handed around, causing several attendees, including a 69-year-old church organist, to “drop like flies” while others burst into song or started dancing.A fleet of eight ambulances was sent to the scene, as well as a rapid response vehicle, two doctors, two clinical supervisors and a Hazardous Area Response Team, trained to respond to serious public health threatsAt last 13 people were rushed to hospital – many so unused to taking drugs they feared they were suffering a heart attack or even dying.A 48-year-old woman from Co Durham was arrested on suspicion of supplying a class B drug and has been bailed while inquiries continue, South Yorkshire Police said.The havoc began when Gary Cook, a keen metal detectorist who is well known in such circles, strolled around the site in the village of High Melton near Doncaster at around 5.30pm on Saturday, offering guests a slice of chocolate cake baked by a female friend to celebrate his 50th birthday. Metal detectorists gather at the Coil to the Soil event in Doncaster over the bank holiday weekend Mr Cook, from Westbury, Wilts, had no idea that the cake was anything other than it looked. His friend Craig Allison, 50, had just packed away his trade stand and was headed back into the main marquee when he bumped into Mr Cook.“He asked me if I’d like a piece of his birthday cake,” he told the Telegraph.“He broke a piece off for myself and a colleague, I wished him happy birthday and ate it as I carried on inside.“It tasted like a normal chocolate cake, it was possibly a bit dry but other than that I didn’t notice any difference.”But around 20 minutes later, as attendees gathered for the raffle, Mr Allison, who runs Crawfords Metal Detectors in Scunthorpe, started feeling dizzy.“At first I thought nothing of it,” he added. “But it got worse and worse and after about 30 minutes I started to feel numb and tingly and then I just collapsed.”Mr Allison was the first victim and those around him assumed he was suffering from heat stroke and called an ambulance.As he drifted in and out of consciousness, he became aware of people talking about “the cake” and asking if he had eaten any.He said: “I started to come around just as the ambulance was ready to take me to hospital but as a paramedic went to shut the door I heard him say, ‘hang on a minute, they’re dropping like flies in here.’ “It’s really quite sad that it snowballed into such a catastrophic event.”Mr Allison said: “We metal detectors have quite an anorak image, which I do not think is true, but I’m worried this will give us a different image altogether.”Up until this point, it had been a perfect weekend with brilliant weather, it was sad that this had to happen, it was a stupid prank that went wrong.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.