Last week, 2 boys were found dead in their Blue Mountains home. Their mum has just been charged.

The mother of the two boys found dead in the Blue Mountains has been charged with two counts of murder.

The two primary school students — Russell Smith, 11, and his brother Ben, nine — were found deceased in their mother's home in Faulconbridge, west of Sydney, about 1pm on Tuesday.

According to NSW Police, the 42-year-old mother was found at the scene with stab wounds, and was taken to hospital in a critical but stable condition.

She was released from hospital on Friday and taken to Parramatta Police Station, where she was charged with two counts of domestic violence-related murder, police said. She was refused bail to appear at Parramatta Local Court on Saturday.

The boys' father, Nick Smith, found his sons at their mother's home and contacted authorities. Police have confirmed the father and mother were separated, with Smith having access to the home but not living there.

Smith said the loss of his sons has caused "unimaginable pain and distress".

In a statement on Thursday, he said:

"The loss of our two beautiful boys has caused unimaginable pain and distress. Russell and Ben were happy, funny, outgoing boys, and were very much loved by their family and friends. Like other boys their age, they loved sports, soccer, the Penrith Panthers, fishing, books, music, spending time with their friends and Max their pup."

"We cannot understand how our boys have been taken this way and we appreciate the kindness and compassion shown by the community."

Smith then requested privacy while he and his family grieve.

Local police commander Superintendent John Nelson has described it as "a very tragic scene". "The Blue Mountains is a very peaceful, community-minded environment so they will be genuinely shocked," he said. The boys had attended school on Monday and police are investigating their movements since then.The mother was known to police for only minor matters and early inquiries had not revealed any history of violence, police said.

NSW Police Commissioner Karen Webb said the boys' father was receiving support.

Flowers, teddy bears and toy cars now lay outside the family home.

NSW Premier Chris Minns said the "horrifying, very distressing" incident was another reminder of the difficult job of emergency service workers.

"I can only imagine what the father of those two boys is going through today and I want to assure him the people of NSW are behind him as he deals with the turning of his life upside down," he said.

"(This) has obviously distressed the people of NSW and I want to assure them every help will be provided to the father of those two boys in the days ahead as he deals with this incredibly distressing situation."

If you or someone you know has been affected by the issues raised in this article, help is always available. Call 1800 RESPECT on 1800 737 732 or Lifeline on 13 11 14.

With AAP.

Feature Image: Supplied/NSW Police.