Key Points:

A youth is fighting for his life after a police chase and serious car crash in west Auckland last night. Police say he was driving a car which had been racing another vehicle on West Coast Rd, Glen Eden.

Police chased two cars for between 10 and 20 seconds, before one of the vehicles, a Honda Prelude, veered across the centreline, narrowly missing an oncoming 4WD and smashing into a footpath, flipping twice.

The young driver - the father of a three-month-old baby - is believed to be in a serious condition in hospital with head and lung injuries, while one of the two passengers in the car suffered moderate injuries. The third person was not injured.

One of the passengers said: "We were driving a bit fast. I don't know why (the driver) was doing it. Maybe he was trying to be cool. The police car started chasing him. He was weaving in and out of traffic."

The other car stopped at the scene and police said its occupants were helping them with their inquiries. One of those occupants, Brendon King, 19, said the two cars were not racing and had been cruising together at 70km/h. However, he said his friend, who was driving the other car, overtook the other car shortly before the crash.

"I got out and ran up to see if (the driver) was OK, and he was still in the car but blood was coming out of his face. Another passenger was lying on the ground, saying his heart hurt."

King said the crash wouldn't have happened if police had backed off.

Police would not confirm the vehicle speeds before or during the chase, except to say they were "well in excess of the speed limit". Several police vehicles were on the scene within seconds.

The Serious Crash Unit is investigating, but the Police Complaints Authority was not involved at this stage, said a spokesman.

A Herald on Sunday photographer was arrested at the scene as he attempted to take photographs.

A cameraman at the scene said: "The pursuit only lasted 10 seconds. The (police) comms controller usually has a warning that says if the chase will endanger you or the public to abandon it immediately. But they didn't even have a chance to reply to that."