Clackline WA crash: Heartbreaking new details emerge as three brothers and their friend are wiped out in horror crash - as top cop makes a gut-wrenching plea to the nation

A police officer has made a gut-wrenching plea to the nation after three brothers and their family friend were killed in a horror accident on a country highway

The three brothers, aged 19, 21, and nine, and their 45-year-old friend, were all killed in the single vehicle crash at Clackline, about 80km north-east of Perth, on Friday morning when their vehicle left the Great Eastern Highway and hit a tree.

In the wake of the tragedy Wheatbelt Superintendent Gene Pears described the accident as 'absolutely heartbreaking' and 'unimaginable'.

'Any loss of life on our roads is a tragedy. But when you lose three young men, three brothers and their family friend in one crash, this is a heartbreaking incident for WA,' he said.

'My heart goes out to the families... when you lose three young men in the prime of their life and their friend, this will have lifelong impacts for that family, for their friends, and for our community.'

The three brothers, aged 19, 21, and nine, and their 45-year-old friend, were all killed in the single vehicle crash at Clackline, about 80km north-east of Perth , on Friday morning when their vehicle left the Great Eastern Highway and hit a tree

The three brothers, aged 19, 21, and nine, and their 45-year-old friend, were all killed in the single vehicle crash at Clackline, about 80km north-east of Perth , on Friday morning when their vehicle left the Great Eastern Highway and hit a tree 

The 21-year-old man was driving the Nissan Navara ute, with his two brothers in the back seat and the 45-year-old family friend in the front passenger seat.   

They were heading east along the Great Eastern Highway when the vehicle left the road about 12.30am.

All four people suffered catastrophic injuries and died at the scene.    

Mr Pears is urging drivers to use caution and stay safe on the roads.

'It's really important that I remind people of the fundamentals of driving on our roads, particularly in regional WA,' he said. 

'Do not drive tired, do not drink and drive or use drugs and drive.

'If you're driving particularly long distances in the dark, in remote locations, take suitable rest periods, wear your seatbelt and please do not touch your phones at all.

All four people - including three brothers - suffered catastrophic injuries and died at the scene

All four people - including three brothers - suffered catastrophic injuries and died at the scene

'It's so important to drive to the conditions, particularly in the country... I can't stress that enough.'   

Western Australia Police told Daily Mail Australia that a major crash investigation has begun to examine the cause of the crash.

Anyone with information that may assist detectives, including dashcam footage, is urged to contact Crime Stoppers on 1800 333 000.