Police have described the fatigue management practices of a trucking company linked to a double fatal accident in Sydney's west last week as "a recipe for disaster".

Two truck drivers, aged 46 and 50, were killed when a prime mover crossed onto the wrong side of the road and collided with an Austral Bricks truck at Erskine Park on Thursday.

The trucks ignited in flames moments after impact, and local factory workers described hearing several loud explosions.

Officers from the Traffic and Highway Command are investigating the crash and today executed a search warrant at a depot operated by the trucking company A.K. Group at Kemps Creek.

The company owned the truck which police will allege was at fault in the fatal collision.

Superintendent Stuart Smith said police examined the company's fatigue management practices and the work diaries of drivers.

"What we've seen this morning is very poor evidence of fatigue management," he said.

"Those documents that we've seized this morning ... will form part of a chain of responsibility investigation.

"The evidence that we've found certainly suggests that there are some major fatigue breaches in some of the trucks that we've investigated this morning."

Police search a truck yard at Kemps Creek raided by police this morning. ( Supplied: NSW Police )

Defect notices issued and trucks seized for further checking

Officers issued major defect notices for two trucks for a range of mechanical and brake issues and oil and fuel leaks, after inspecting 14 trucks.

They also issued several minor defect notices, with problems with the trucks also including bald tyres.

NSW Police say the audit may help bring closure for the victim's families. ( ABC News: Jessica Kidd )

Several of the company's trucks were taken to the Roads and Maritime Service inspection facility at Wetherill Park for further examination.

Superintendent Smith said the outcome of the investigation would determine whether the company will face charges over last week's collision.

"Nothing's off the table with the investigation," he said.

"We've got at least two families that need to know what occurred and we're going to do everything we can to make sure that they get closure."

Police also recovered a car which they will allege is stolen and linked to an aggravated robbery at Dubbo in the state's Central West.

Traffic and Highway Patrol Acting Assistant Commissioner David Driver said safety should be the priority for all heavy vehicle operators.

"With defects, fatigue, and other issues identified, we will work closely with Roads and Maritime Services to ensure operators are complying in the hope that we can prevent future tragic events," he said.

"Operators should be aware of their obligations; it is too late when the police and Roads and Maritime Services turn up at your depot."

Police have raided the truck yard where a truck involved in a fatal crash was from. ( Supplied: NSW Police )

Trucking company director rejects allegations

A.K. Group director Ammar Kejer rejected the allegations and said his company had been unfairly targeted.

"They couldn't find any problems, they just make [my job] hard," he said.

"They didn't call me to say they were coming, they just came at 5 o'clock in the morning."

Mr Kejer denied suggestions his company did not properly manage fatigue amongst its drivers and said the driver involved in last week's accident was within the standard 12 hour work limit.

"He was one of the best drivers in Sydney and he was driving the best truck in Sydney," he said.

"They've got all his diary books, they couldn't find [anything] wrong."