A clash between two groups in the Muthiganj area of Allahabad on Friday resulted in a blast, which left one person dead.
The cause of the explosion is still to be ascertained.
"The clash, which was between two groups of people, occurred during Holi celebrations. Four people have been arrested for the same and will be interrogated," Senior Superintendant of Police Deepak Kumar told ANI.
"One person has been left dead. The reason behind the blast will be known after the post-mortem report comes out," he added.
Further details are awaited.