A woman will be assessed in hospital after she allegedly decapitated her mum with several knives before dropping the 57-year-old’s head out the front of a neighbour’s home in Sydney’s northwest.

Jessica Camilleri, 25, faced Parramatta Bail Court today charged with murder after she allegedly attacked her mum Rita in the kitchen of their St Clair home late last night.

Rita had been babysitting her four-year-old grandson, Jessica’s nephew, at the time.

Police confirmed the boy witnessed the tragic event.

Ms Camilleri did not apply for bail, with her lawyer telling the court she had significant health issues.

Magistrate Michael Price made an order for her to be assessed in hospital before her next court appearance.

The 25-year-old, who appeared via video link, told the court she was injured in the incident and was unable to wash herself properly to “get all the blood off” because she couldn’t move her fingers properly.

She told the magistrate she had a number of conditions including border autism, bipolar disorder and anxiety.

It’s alleged the 25-year-old used a “number of knives” to kill her mother and cut off her head — before dropping it on the footpath outside their family home just after 11.30pm last night.

Support is being provided to the first responders who witnessed the horrific scene with police describing it as “as bad as it gets”.

Police allege Rita was killed by her daughter in the kitchen of their family’s St Clair home, where they both lived, before the 25-year-old carried her head two houses down the road.

Speaking to reporters this afternoon, Nepean Police Area Commander Detective Superintendent Brett McFadden said “this is up there with one of the most significant, most horrific scenes police have had to face”.

Police rushed to the St Clair Ave home just after 11.30pm last night to reports of two women arguing.

Mr McFadden said the information they received from neighbours was “quite specific”.

News.com.au understands neighbours started to rush to the aid of the mother after hearing the “violent argument” but were instead confronted by the 57-year-old’s head on the footpath.

Officers rushed to the scene and found the mum’s head and later found the rest of her dismembered body inside the kitchen of their St Clair Ave home.

Mr McFadden said the mum had suffered “extensive injuries”.

“We understand at this stage that a number of knives were used during the course of the incident. I am not able to specify what kind of knives they were at this stage. They both reside at the home together,” he said.

The woman’s 25-year-old daughter was arrested in the front yard of a neighbour’s home.

“There is no stepping away from the fact that this was horrific and a significant attack,” Mr McFadden said, commending the professionalism of police.

Mr McFadden said the 25-year-old was known to police but “there was no information that this situation in the family home was likely to occur”.

Ms Camilleri was caring for her four-year-old grandson when she was allegedly murdered by her daughter.

The four-year-old was taken to Westmead Children’s Hospital with a small head injury and is now being cared for by his family.

Mr McFadden said the boy had witnessed the alleged crime.

“The family is distraught as to what has taken place,” he said.

A knife was seized for forensic examination and several crime scenes have been established inside the home, police said.

Detectives have established a strike force to further investigate the incident.

The 25-year-old will face Parramatta Local Court later today, charged with one count of murder.

If you or anyone you know needs help, please contact LifeLine on 13 11 14 or visit https://www.lifeline.org.au.

If you or someone you know is impacted by sexual assault or family violence, call 1800 RESPECT on 1800 737 732 or visit www.1800RESPECT.org.au. In an emergency, call triple-0.