Deputy President William Ruto's pilot, Captain Mario Magonga, has died in a chopper crash in Turkana County.
Police on Monday said Captain Magonga died with all the four Americans he was flying after their helicopter came down at Lobolo in Central Island National Park at 8pm.
"Available information indicates that two helicopters had landed earlier at Lobolo tented camp on the National Park's Island, however one managed to clear the area safely," the National Police Service said in a statement.
"Security personnel dispatched to the scene confirmed that among the five were four Americans and the Kenyan pilot."
Security teams have been dispatched to the scene to assist with recovery of the wreck and the bodies, police said.
"The cause of the incident is yet to be established and the details of the deceased will be released once the next of kin have been notified."
Kitutu Chache South MP Richard Onyonka, a relative of the deceased, said the chopper Mr Magonga was flying went off radar near Lake Turkana.
He said following a search and rescue mission, the wreckage of the aircraft and the pilot's body were located on Monday at 2am.
"He (Magonga) went off the radar and they were unable to trace him until about 2am when they found his wreckage. The only thing we know is he was the one flying the helicopter," he told NTV.
It was not immediately clear what caused the crash and Mr Onyonka called on the Kenya Civil Aviation Authority (KCAA) to investigate the disaster.
Captain Magonga, a former Kenya Defence Forces pilot, hails from Nyamataro, Kitutu Chache South, Kisii County.
On his LinkedIn page, Captain Magonga says he was working with KIDL Helicopters based at Wilson Airport in the capital Nairobi.
KIDL Helicopters, which he joined in March 2017, describes him as "Chief Pilot, (ATP) and a qualified helicopter Instructor trained in the Kenya Defence Forces."
"He has accumulated over 5500hrs experience on single and multi-engine types," his brief profile reads.
In its description, the company says it specialises in high-end air travel, filming and photography, tracking, security, medivac, aerial work as well as sport and leisure travel
"We feel proud to say that we have the capability and expertise to undertake some of the most difficult helicopter missions for search and rescue, disaster relief, aerial work and leisure and pilgrimage tours," KIDL Helicopters says.
Captain Magonga also worked for Tropic Air Kenya until June 2015, when he left to pursue his flying career.
"An exceptional helicopter pilot, Mario has also been the source of strength, laughter and spirit, both in the office and in the air, and we will miss him," Tropic Air says in a June 23, 2015 Facebook post.
The late captain has has been described as a pilot "with exceptional flying skills", with Mr Onyonka, his cousin, saying he had been cleared to flying high-profile guests, including former US President Barack Obama.
"Mario was one of the best helicopter pilots that money could buy," Mr Onyonka told NTV.
"Mario was cleared to fly from Barrack Obama to State Department officials and the American ambassador, Mario was one of the best money could train."
The Turkana crash comes barely three weeks after a light fixed-wing craft came down in a forest at Londiani in Kericho County, killing all its five occupants.
The frequency of the crashes has brought Kenya's air safety record into question.