Three members of the same family died when the Polish supermarket and a two-storey flat above it on Hinkley Road were destroyed around 7pm last Sunday. The latest arrests bring the number of men in custody over the blast to five, after three were detained by police on Wednesday, Leicestershire Police said in a statement.
Three men have appeared in court after allegedly starting a fire at a shop using petrol.
Two other men, who are both from East Anglia and who were arrested on Friday, remain in police custody and continue to be questioned by detectives.
The shop's owner Aram Kurd, 33, and co-defendants Hawkar Hassan, 32, and Arkan Ali, 37, appeared at the city's magistrates court today each charged with five counts of manslaughter and one count of arson with intent to endanger life.
Ali, from Oldham, Hassan, of no fixed abode, and Kurd, from Leicester, looked straight ahead as they followed the proceedings through a Kurdish interpreter.
Five people were taken to hospital after the explosion, including one with critical injuries.
The fifth body is still to be formally identified but is believed to be Mary, officers said.
The man, in his 40s and from East Anglia, is being held on suspicion of manslaughter.