Heckenburg smash: NSW Police launch manhunt after two people killed in fatal multi-vehicle collision

A police manhunt is underway after the occupants of a Mercedes involved in a horror crash that left two people dead in southwest Sydney fled the scene.

Emergency services were called to Sadleir Ave in Heckenberg around 9:20 p.m. Friday and received reports of a multi-vehicle collision.

It is believed that a black Mercedes collided head-on with a Toyota Echo before hitting a Toyota RAV4 and landing on its side.

The occupants of the Mercedes then got out of the overturned car and fled in a Volkswagen Golf.

The driver of the Echo (pictured), 24, and her 15-year-old passenger were treated at the scene by paramedics but could not be rescued

The driver of the Echo, a 24-year-old female, and her 15-year-old male passenger, were both treated by paramedics at the scene of the collision.

It’s clear the pair were siblings, with the older sister picking up her younger brother after he completed a shift at his new job at Kmart.

Both died at the scene and have yet to be formally identified.

The 18-year-old male driver of the Gulf, who was located in Ashcroft by police, was arrested at Liverpool Police Station (photo, scene)

The two occupants of the RAV4 were not injured.

A crime scene was established and the Mercedes was subsequently seized by police and later subjected to forensic examination.

The 18-year-old male driver of the Golf, who was located in Ashcroft by police, was arrested at Liverpool Police Station around 11:30pm.

He was taken to Liverpool Hospital for mandatory tests.

Police have urged the occupants of the Mercedes, or anyone else with information about the incident, to contact Crime Stoppers.

A crime scene was set up and the Mercedes was then seized by the police and later subjected to forensic examination (pictured)