Detectives are investigating the murders of a mother and her three children as a possible revenge attack launched after a man was killed.
Shehnila Taufiq, who was in her 40s, died along with her 19-year-old daughter and sons, aged 17 and 15, when their home was engulfed in flames.
The children were named by the local mosque as Zainab, Jamal and Bilal.
Emergency crews battled to save the family but the four victims were found dead inside the bedrooms of the terraced house in Wood Hill in the Spinney Hills area of Leicester just after 12.30am today.
Mrs Taufiq’s husband, Mohammad, is believed be returning home from Ireland where he works as a heart surgeon, a friend said.
Leicestershire Police launched two separate murder inquiries within 24 hours.
The first began after officers were called at 5.30pm yesterday to reports that a man in his 20s had been assaulted in Kent Street - just half a mile from the blaze which erupted several hours later.
He was taken to Leicester Royal Infirmary where he died.
Today, as police appealed for information, Assistant Chief Constable Roger Bannister said officers were investigating a theory that Mrs Taufiq and her children were killed in revenge for the earlier attack.
He said: “These are obviously both very serious incidents and the investigations are in their very early stages to establish if there are any links between them.
“I can’t confirm here and now it is a revenge attack - it may be, it may not be - but lines of inquiry will certainly get to the bottom of that.”
Referring to neighbours talking about a “fire-bombing”, Mr Bannister added: “Fire-bombing, in my experience, means different things to different people.
“We are working really closely with the fire brigade. Exactly how the fire started, where it started and of course who is responsible is something we will get to the bottom of.”
Urging witnesses to get in touch, Mr Bannister said it was possible that both offences, which he described as “terrible, terrible crimes”, were linked.
He said the crimes might be linked because of the close locations and short space of time between them.
The officer said neither the family nor the man who was killed were known to police.
A mosque attended by the Taufiq family issued a statement expressing shock at the deaths.