Keiyo South Sub-County police commander Abdullahi Dahir confirmed the deaths.
Dahir said the cause of the accident that killed the world's fastest marathoner could not be immediately established.
He said Kiptum and his coach died on the spot, as a result of the impact.
"We received a report that an accident had occurred at 11:17pm at the junction to Flax area along Eldoret-Ravine road. The area is at times foggy and many cows are on the road at night," said Dahir.
The police commander continued: "Upon arrival, the police established that world record holder Kelvin Kiptum and his coach Gervais Hakizimana were dead.
"A woman, Sharon Kosgei who was in the back seat sustained injuries and is receiving treatment in Eldoret," Dahir said.
The police took Kiptum's body and that of his coach to the Racecourse Hospital morgue. The athlete's remains were on Monday transferred to the Eldoret Hospital.
"It is sad that the country has lost an athlete of Kiptum's stature," Dahir said, adding that investigations into the exact cause of the crash are ongoing.
Frederick Mutai, a public service driver who was among the first people to arrive at the scene said he heard the injured woman crying.
"I called the police who arrived a few minutes later. We rushed the injured woman for treatment," Mutai said.
The accident ended Kiptum's meteoric rise to stardom.
Before then, Kiptum had won Kass half marathon in 2019 but had not taken part in international races.
According to relatives, Kiptum did not proceed to secondary school, choosing to train as an artisan electrician before training in Kaptagat forest without a coach while herding his father's cows.
He started off his journey to marathon stardom by winning the Valencia Marathon in December 2022.
He went ahead to win the 2023 London Marathon in a course record before shattering the world record at the Chicago Marathon in October.
Last October, Kelvin Kiptum, a 24-year-old athlete from Chepsamo village in Elgeyo Marakwet ran 2:00:35 shaving 34 seconds off the previous mark set by Eliud Kipchoge, who is the second fastest of all time in the marathon.
He stunned the world with the fastest mark at the Chicago Marathon on October 8, further raising eyebrows.
A battle between Kiptum and Kipchoge at the 2024 Paris Olympic Marathon in August is a clash that the world was yearning to watch, this year.
In December, he was named the World Athlete of the Year 2023 in the long-distance category.
He has left a widow Asenette Kiptum and children Kigen, 4, and Cherop, 7.