In seconds, two cars were written off and one damaged after 40 litres of oil was apparently thrown across a road in the Royal National Park.
Police believe saboteurs dumped up to 40 litres of oil on a dangerous bend on Sir Bertram Stevens Drive, near the Warumbul Road turn-off, late on Saturday evening.
''Whoever did this is someone who doesn't care about other people's lives,'' said Inspector Rod Rae, of Sutherland Police.
''I'd throw everything at them; everything short of attempted murder. We could have lost a couple [of lives].''
The driver and passenger of one of the cars, which was written off, were taken to hospital with minor injuries.
A second car was written off, while the third had only slight damage.
The road was closed for three hours while detectives investigated and sand was spread to soak up the oil.
''You can see where the oil has been thrown,'' said Inspector Rae. ''They have done it very intentionally. I can't think of any other reason to do this other than to cause someone grief.''
Later in the morning a motorcyclist also lost control on the sand-covered oil but escaped injury.
Shortly before the multiple accidents, which happened about 11.25pm, one witness was nearly forced off the road by a car that was part of a convoy of about 15 high-performance cars entering the area.
''I had to swerve off the road,'' said the man, who did not wish to be named. ''I was going to turn around and chase them but I wouldn't have been able to remember which one it was.''
One theory is that the oil might have been placed by car enthusiasts who have long used the Royal National Park as a night-time venue for illegal drag racing and drifting.
However, Inspector Rae said it was unlikely drifters were responsible.
''This is not a common thing for drifters to do,'' he said. ''They don't need to do that. They drift without oil.''
The chief executive of the Confederation of Australian Motor Sport (CAMS), David Morgan, condemned anyone using public roads for ''sport''.
''By its very definition, motor sport is conducted in a controlled environment at venues that have been selected and developed with safety as our paramount concern,'' he said. ''CAMS does not condone inappropriate or irresponsible driving behaviour on public roads, and such activity should be dealt with appropriately by authorities.''
Any witness to the events is asked to contact Sutherland Police or Crime Stoppers on 1800 333 000.