A woman has died after a car ploughed through her home in Western Sydney.
Emergency services rushed to the property on Monfarville Street in St Marys at around 5:00am on Saturday.
They discovered an SUV had crashed through the front of a house with four people inside.
One of the residents, a 62-year-old woman, sustained serious injuries.
Paramedics tried to save her, but she died at the scene.
The three other people inside the home were unharmed.
Shortly after the crash, a 29-year-old woman carrying a baby was stopped by officers on the street nearby.
Police allege the woman had been driving the car as it ploughed into the house, before fleeing the vehicle and running from the scene with her baby.
She was arrested and taken to Nepean Hospital for mandatory drug and alcohol testing.
Fire and Rescue NSW spokesman Samuel Parkhouse said the house had been badly damaged and is being assessed for safety, after the vehicle became "airborne".
"From the damage we've seen it appears the car, as it's come into the property, has become airborne and has gone straight through from the front all the way through to the rear of the property," he said.
He said he had not seen anything like it before.
"The car has gone straight through the house," Mr Parkhouse said.
"It is significant structural damage to the house, it will need to be assessed by an engineer to determine whether it will be habitable.
"We've used equipment to shore up the structure to make it safe for ongoing investigations."
The impact of the accident was so intense that the car smashed through the weatherboard home and crashed into the back shed.
“At the scene, it was quite clear the car went right through the house and ended up in the backyard,” a NSW Police spokesperson said.
A relative of the woman arrived at the scene and was seen taking the baby away in a car.
Police said neither the woman nor the baby sustained any significant injuries.
A neighbour said he was up just before 5am when he heard a thump which sounded like a car accident but couldn't see anything from his window.
"I was sure I heard what I thought I heard, then all of a sudden the flashing lights are coming and then I came out and I looked up and went 'where's the car?'.
"And it's gone through the house and then one of the people came out and said someone had been hurt."
Neighbour Charlie Eliaba, who eventually called the police, also couldn't place the source of the "loud bang".
"Then I walked up here, saw the fence knocked down and saw the big opening, and then I rang the police. And the a lady walked out with a baby, I think she was in shock.
"It's pretty sad, [my] neighbour they're good people, very nice people."
Footage of the house after the crash shows the front right room of the property was severely damaged.
The unharmed occupants of the house were seen huddled on the street outside the property wrapped in blankets.
A crime scene has been set up and police said investigations were underway into the circumstances of the crash.
Police are urging anyone with information, CCTV or dashcam footage to contact Crime Stoppers.
