This article was reproduced with the kind permission
of the British Broadcasting Corporation
21 November 2007, 10:59 GMT
Robert Griffiths, 57, suffered serious burns in the blaze on Lowlands Walk, Askern, Doncaster, on 12 November. He died in hospital six days later.
Two other residents, aged 36 and 49, and a neighbour who tried to help suffered minor injuries.
South Yorkshire Police said two boys, aged 16 and 17, and a 14-year-old girl were being questioned by detectives.
On Monday officers issued an e-fit of a man they want to speak to about the fire.
They said he was seen standing near the flats with another male a short time before the fire was reported.
The fire was deliberately started in or near the flats' bin store and then spread to the communal area of the four-flat block, police said.
Mr Griffiths managed to escape, but died from severe burns and the effects of smoke inhalation.