NSW woman critical in crash with 14yo

A woman who was badly injured when her ute crashed head-on with a car driven by a 14-year-old boy in Sydney's west is in a critical but stable condition 24 hours after the smash.

The 27-year-old woman suffered extensive injuries to her arms and legs when her ute collided with teenager's car at Werrington on Thursday night.

Critical care paramedics worked on her for an hour while emergency crews tried to free her from the wreckage, a Careflight spokesman said on Friday.

Her 16-year-old passenger was also taken to Westmead Hospital with leg injuries. He's in a stable condition.

Four teenagers, aged between 14 and 18, in the other car were taken to The Children's Hospital at Westmead for a range of non-life threatening injuries, NSW Police said.

A 14-year-old boy from Bidwell, who was behind the wheel at the time, suffered serious abdominal injuries and fractures.

A Werrington resident took to social media to express their surprise that a teenager was driving the car.

"He shouldn't have even been driving ... 14-years-old is way too young," they wrote on Facebook.

Another Sydneysider wrote: "These things happen due to speed limits being ignored and hoons who think it will never happen to them - and most times it's the innocent who suffer."