Zabka mini-supermarket and a flat above were completely destroyed in the blast on the evening of February 25, killing three members of the Ragoobeer family who had moved to the UK from Mauritius.
Three men charged with arson and manslaughter appeared before Leicester Magistrates Court and were remanded in custody to appear before Leicester Crown Court on April 3.
The store's owner Aram Kurd, 33, is charged along with Hawkar Hassan, 32, and Arkan Ali, 37.
"It has been established that the explosion was caused by petrol and the petrol was spread throughout the shop," prosecuting solicitor Zoe Lee told the court.
The three men each face five counts of manslaughter and one count of arson with intent or being reckless as to whether life was endangered.
Last week, the police had formally identified brothers Shane Ragoobeer, 18, and Sean Ragoobeer, 17 as the victims of the blaze. They lived in the flat above the Polish shop. Their mother, 46-year-old Mary Ragoobeer, is yet to be formally identified but is believed to be the unidentified body.
The court heard that Ali's partner was 22-year-old shop worker Viktorija Ijevleva, who died in the explosion, besides Shane Ragoobeer s girlfriend 18-year-old Leah Beth Reek.
Two other men, both in their 30s, who were arrested on Friday have been released.
The police have also made a fresh witness appeal for anyone who may have been near the mini supermarket on February 25.
It s vital that we speak to anyone who may have information about any people they saw coming and going into the supermarket in Hinckley Road in the hours leading up to the explosion People lost their lives in the most horrific way on Sunday. We owe it to them to understand the cause of that explosion, said Detective Inspector Michelle Keen.
The force said that the scene of the fire will remain cordoned off as specialist officers and experts from other agencies continue their work to sift through and examine the rubble in the search for clues.
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