Two teenagers have been arrested in relation to an attack and fire at an elderly woman's home in Ranui.

Photo: RNZ / Claire Eastham-Farrelly

The 88-year-old woman's window was smashed and her sofa was set alight.

A 14-year-old girl and an 18-year-old man will appear in the Waitākere Youth Court tomorrow charged with burglary and arson. The 14-year-old also faces a charge of wilful damage.

Police said three young women and a young man knocked on the woman's door about 10pm on Sunday night and asked for a drink of water, which the woman gave them.

They later returned and were asked to leave. Two of the young women smashed one of her windows before leaving, police said.

With the help of a neighbour, the elderly woman placed a sofa against her window to secure it and went to bed, but a smoke alarm later woke her and she discovered the sofa was on fire.

A police officer described the attack as one of the worse displays of violence against an elderly person he had seen.

When RNZ visited this afternoon, a piece of plywood had been nailed over the window.

The woman, who RNZ has chosen not to identify, said she hoped the young people would be caught and get the help that they need.

Her neighbour said she was alerted to the fire by teenagers.

"I was adamant: 'Darren' - my son - 'get in there and find her' because, not knowing how much smoke was in there."

She said her son jumped over the fence with a garden hose to put the fire out.

"So I just yelled out at the top of my breath: 'help, fire, help us please, if anyone can hear us, come over and help us'."

She said they were joined by another neighbour who turned his garden hose on the flames as well.

The neighbour told RNZ she saw the teenagers looking in cupboards in the kitchen.

"These little hounds had tormented her from before Christmas and they persisted and persisted. And all she can feel for them is the love. That is beautiful, that is awesome but they do need help, they do."

She said the incident was a timely reminder for everyone to keep an eye out for their neighbours.

"Everyone should get to know their neighbours, regardless of who or what they are, you know? Nothing should hinder anyone from getting to know their neighbours."

While the elderly woman was not injured, Detective Senior Sergeant Roger Small said police were taking the matter very seriously and were following positive lines of enquiry.

"An innocent elderly victim was targeted in her own home, a place where she should have been able to be safe and feel safe."

Mr Small told RNZ he was disgusted by the attack, which was one of the worse displays of violence against an elderly person he had seen.

"There has been a previous incident where there was some unwanted attention given, but not to this nature. It's not a common occurrence, normally the elderly community can live quite comfortably in west Auckland, so that's why we want to make sure we get on top of this immediately and don't see any recurrence."

Police urged anyone with information to call them as soon as possible.