Yet they were barely halfway home from the Psyfari festival when their P-plate driver spun out of control on the Bells Line of Road at Bilpin and veered into oncoming traffic, crashing head-on with a Subaru carrying a couple in their 80s.

Northern Beaches friends Lachie Burleigh, 17, Ben Sawyer, 19, and Luke Shanahan, 21, were killed instantly in the horrific crash just after 3.30pm.

Their P-plate driver, just 17 years old and from Freshwater, survived with minor injuries. The elderly couple in the Subaru sedan also escaped with minor injuries.

The crash was the latest in a disturbing spike in the state's road toll. So far this year, 235 people have been killed, 26 more than at the same time last year.

It prompted a widespread crackdown by police, who conducted Operation Saturation on roads and at hot spots over the weekend.

However, nine people died in seven crashes after the operation began on Thursday.

Traffic and Highway Patrol Commander John Hartley was both devastated and furious on Monday, blaming the "tragic loss of life" at Bilpin and elsewhere on poor driver behaviour and responsibility.

"With what have been perfect weather conditions, some road users are taking their driving for granted," he said.

"Over the past couple of days, officers have seen countless motorists showing a total lack of respect for other road users, and we are showing zero-tolerance to this type of behaviour."

Fairfax Media understands the P-plate driver has been drug and alcohol-tested and will be questioned by police once he recovers from minor injuries in Westmead Hospital.

It's understood he was coming around a sweeping right-hand bend when the wheels of the Mitsubishi SUV slid off the side of the road. The weather was fine and the road was dry, new bitumen.

In an eerie Facebook post just four days before the crash, Lachie's older brother, Jayden, who lives in the Northern Rivers region, pleaded with drivers to slow down.

"To all you northern rivers rev head road Reverends ... Please slow down! Your selfish mind in your powerfully driven ego chariot is not wanted on these roads ... Especially in slippery lightning & thunder times!" he posted.

Friends expressed their shock on Sunday night, having danced with the men in the bushes of the Capertee Valley just hours before hearing news of their deaths.

"I'm glad I got to spend your last moments partying with you just like you would have wanted," Tim Stanton posted about Mr Shanahan. "Wish I could wake up and this was all a bad dream but it is real."

A friend of Lachie's and fellow year 12 student at Oxford Falls Grammar School said: "I can't believe this has happened, from dancing with you only hours ago to hearing that one of my closest mates and brothers has had an accident. I will never forget your happy vibes and constant smile."

Lachie's brother, Jayden, posted: "My little bro man, thank you for giving me that special strength. It's just really hard for me right now trying to fathom turning this into a reality."

Just half an hour before the Bilpin triple fatality, Joshua Michael Young was killed when his motorcycle smashed into an oncoming Mazda sedan on Barkers Lodge Road, Picton.

His father, who was riding behind him on the winding, scenic road on the outskirts of Sydney, witnessed the crash and held his dying son in his arms, according to a witness.

Fairfax understands Mr Young, aged in his 20s, took a corner badly and clipped oncoming traffic.

Craig Sheahan, one of the first on the scene, said Mr Young  "was lying on the road and in a bad way" and "his father was there cradling his son".

"Things got worse, the rider was in need of CPR, I commenced, it seemed like an eternity till the ambulance arrived," he said.

"I don't think it was going to end well for the rider and my ride home afterwards was very different, lots of time to think about things."

Mr Young was a competitive motorbike rider and race car driver, a keen traveller and a talented artist who enjoyed frequent weekend rides with his father.

Assistant Commissioner Hartley said the spike in fatalities since May has been fuelled by an unusual number of pedestrian, passenger and elderly driver deaths.

He said Operation Saturation, funded by the Community Road Safety Fund, will run until September 28.