Tuaran acting police chief ASP Juraimah Ismail said Koh Tze Guan, 62, succumbed to serious injuries on his head and body.
He was pronounced dead at 12.15pm at the district hospital here.
She said Koh was driving a Toyota Prado with his 59-year-old wife, Lim Nyuk Ping from Kota Kinabalu to Ranau to attend an official function when the tragedy struck at 9.30am.
A Proton Persona driven by a 36-year-old man with a 36-year-old woman was behind the Prado.
After ramming the Prado, Juraimah said the trailer also crashed onto the Persona, which caused the vehicle to turn turtle at the roadside.
"Our investigation revealed that the trailer driven by a 34-year-old man together with his 30-year-old attendant was coming from Ranau to Tamparuli.
"Upon reaching a bend, the driver lost control when going down a hilly road at the scene and rammed the two vehicles from the opposite lane," Juraimah said when contacted.
She said the trailer driver and his attendant managed to get out of the vehicle before fire broke out and gutted the trailer's cabin.
She said the deceased was trapped inside the Prado and firefighters were alerted to extricate him.
"The deceased's wife only sustained light injuries on her head and right hand while the trailer's driver and his attendant only sustained light injuries. As for the Persona driver, he suffered serious injuries on his left knee and head while his female passenger sustained minor injuries on her chest, abdomen and neck," Juraimah said.
She said the case is being investigated under Section 41(1) of the Road Transport Act 1987 for reckless driving causing fatal mishap and urged anyone who witnessed the incident to come forward to assist police investigation.