Police found a dying woman and a gruesome scene after they broke into a home on Sydney's northern beaches last night.
Neighbours had raised the alarm after hearing an argument between a man and a woman at a small first-floor unit in Pitt Road, North Curl Curl.
Officers smashed the door down about 9.20pm (AEST) and found a woman, aged about 32, with critical injuries.
Paramedics tried to revive her but she died at the scene a short time later.
"The scene was a very unpleasant one," Acting Superintendent Graeme Pickering told reporters.
Detectives believe the woman's attacker was male and had fled the scene, but would not elaborate on whether the dead woman had a boyfriend or whether she lived at the unit.
Although the woman's killer was on the run, Supt Pickering said he did not think northern beaches residents should feel concerned.
He urged the man to hand himself in.
"At the moment we'd be seeking assistance from the public initially just if they saw anyone acting suspiciously in the vicinity of the unit last night," he added.
"We don't have a description at the moment.
"Domestic-related violence will be a line of inquiry. But obviously we'll check everything."
An autopsy on the woman's body is due to be completed on Tuesday morning and should reveal more information about any weapon used in the attack.
Police expect to name the woman later on Tuesday.
The block of units where the woman died, Victoria Court, remained sealed off with police tape on Tuesday afternoon.
Officers from the Public Order and Riot Squad (PORS), often called upon to help during big police investigations, were searching for evidence in the roads immediately around the building.
Forensic science specialists were also seen entering the unit block wearing blue overalls.
Local residents said they were shocked by the incident.
"There's a few people who are wondering if we're in danger but personally I think whoever did it is long gone," Lindsay Taylor, a Pitt Road resident told AAP.
"You just hope the police do their work quickly and catch whoever it is."
