Police investigating a murder possibly linked to the fire in Leicester which killed Shehnila Taufiq and her teenage children Zainab, Jamal and Bilal have arrested a man and two women.
The three, all aged 19, have been held over the killing of a man in his 20s in Leicester. Police said the man was arrested in London.
They believe the family may have been killed in a revenge attack.
Neighbours think it may have been a case of mistaken identity when their home was engulfed in flames early yesterday.
Police have said they cannot rule out a link between the two events and they are investigating whether the fire was started intentionally as a revenge attack. Neighbours of the family reacted with disbelief to the idea that they could have been intentionally killed and claimed they may not have been the intended target.
A middle-aged man, who did not want to be named, said: "Most people feel this was meant for somebody else and they got the wrong house."
Leicestershire Police launched its first murder inquiry shortly after 5.30pm on Thursday when a man in his 20s was taken from Kent Street – half a mile away from the scene of the fire – to hospital where he died.
A second inquiry began when neighbours reported flames shooting out of the first floor of the Sattar family home at 12.30am yesterday. 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: "I can't confirm here and now it is a revenge attack but lines of inquiry will certainly get to the bottom of that."
Urging witnesses to get in touch, he said it was possible that both offences, which he described as "terrible, terrible crimes", were linked.
Leicester-based Imam Ibrahim Mogra visited the scene.
He said: "It's hard to believe that such a tragedy could occur and four lives could be lost in a matter of minutes."
Local shopkeeper Sattar Raidhan, who has lived in the area for 35 years, said: "I can't even imagine how this would happen to a family like that."