Three people killed in a fire at an historic former station house in Rushton have been named as Emma Conn, 30, her four-year old daughter Mayci Fox and 23-year-old Louie Thorn, Northamptonshire Police said.
Police arrested a 54-year-old man on suspicion of murder following the incident, but he was later released without charge on Sunday.
An investigation into the cause of the fire is ongoing.
Formal identification of the victims is yet to take place but police said the families agreed to the names of the deceased being shared publicly.
Mayci and her mother, Ms Conn, are from Desborough, and Mr Thorn is from Rushton.
Detective Chief Inspector Ruby Burrow, of the East Midlands Special Operations Unit, said in a statement: "It is only right that an incident such as this is treated with the utmost seriousness, to make sure we have done all we can to understand what has happened for the sake of those who have died and their loved ones.
"In some cases, this requires arrests to be made in order to best secure potential evidence.
"Our team has been working at pace on this investigation and after rigorous examination of the available information, we do not believe there is any evidence of criminal wrongdoing at this point.
"As a result, the arrested man has been released without charge and will now be supported by specialist officers as he continues to assist the investigation team.
"The families involved have been kept updated on this development and I would repeat our request for their privacy to be respected at this incredibly distressing time."
One person was taken to hospital by East Midlands Ambulance Service following the fire.
They, as well as three police officers, were assessed for smoke inhalation.
Photographs showed severe damage to the roof of the building - a Grade II-listed building and a former station master's house at the now-closed Glendon and Rushton railway station.
