Mary Fox helped her 17-year-old son jump out of a window on the first floor
Three teenagers have been arrested on suspicion of murdering a woman in Cornwall by pushing a firework through her letterbox.
Mother-of-nine Mary Fox, 59, of Wallace Road, Bodmin, died in the fire on Thursday evening.
An 18-year-old man and two 17-year-old youths from the Bodmin area have all been held on suspicion on murder and are in custody awaiting interview.
Ms Fox's 17-year-old son, Raum, escaped from the property and raised the alarm.
No harassment complaints
Police have played down reports from neighbours that Ms Fox's son had mild learning disabilities and may have been harassed by local youths.
The remnants of a firework were found behind the front door of Ms Fox's house.
They said the Fox family had made no complaints about harassment and there was no obvious evidence of intimidation or bullying to either Ms Fox or her son and that such suggestions were "purely speculation" and "unfounded".
Firework remnants were found behind the front door
Police revealed over the weekend that they were planning to examine social networking sites on the internet as part of investigations into Ms Fox's death.
It followed speculation about identities of the culprits being posted on the web and names being "bandied about".
At the start of the investigation a force spokesman claimed that the "key to solving the murder inquiry" lay within the local community of Bodmin.
Officers stepped up patrols on the Berryfields estate where Ms Fox and her son lived and carried out door-to-door inquiries over the weekend.
Det Ch Insp Paul Burgan said officers were "investigating some positive leads from the community in Bodmin".
The remains of fireworks found in the street were also collected for potential evidence.
Raum Fox alerted neighbours that his mother was inside the burning house
Detectives have stressed that, despite the arrests, they were still in the early stages of the investigation and were continuing to appeal for people with any information to contact them.
Ms Fox, whose family have described her as a "loving, caring and self-sacrificing woman", is believed to have gone back to rescue her cat after helping her son escape.
The teenager ran to alert neighbours that his mother was still trapped inside but when fire crews entered the property they found she had already died.
Floral tributes have been placed outside the family home and the mayor of Bodmin, Bob Micek, said that the whole community was "shocked" at the incident.
He said: "They're quite traumatised actually about the whole thing.
"It's not something we'd expect to happen in our town and it's not something we'd expect to happen nowadays on Berryfields Estate."
The arrested teenagers are in custody at Launceston police station.