A cylinder exploded in a tent at the Digambar Ani Akhara at the Kumbh Mela site in Prayagraj, triggering a massive fire on Monday, a day before the fair officially opens, police said. There were no immediate reports of any one being injured, Akhara police station inspector Bhaskar Mishra told PTI. Fire fighters rushed to control the blaze which engulfed the makeshift structure at the venue.