The accident occurred in the Ngong hills on the outskirts of the Kenyan capital.
All six on board were burned beyond recognition.
Police refused comment and said government officials were en route to the scene of the crash in the Ngong hills on the outskirts of the Kenyan capital.
The reason for the crash was not immediately clear.
A source earlier said some bodies were charred beyond recognition.
UPDATE: New report says 6 people died. Kenyan interior minister George Saitoti and his assistant, Orwa Ojode, Perm Second, Mutea Iringo and 4 others were reportedly killed in the helicopter crash.
UPDATE 2: A spokesman said Raila Odinga, the Kenyan prime minister, had been informed of the deaths of George Saitoti, his internal security minister, and Orwa Ojode, his deputy.
UPDATE 3: Vice president Kalonzo Musyoka and commissioner of Police Matthew Iteere arrive at the scene of the crashed police helicopter in Ngong.
UPDATE 4: Speaker of national assembly Kenneth Marende joins Kalonzo and Iteere at the scene of police helicopter crash. Kalonzo confirms 6 dead.
UPDATE 5: Saitoti, an American-trained economist and mathematician, was one of the most visible figures in Kenyan politics. He announced last year that he would seek the Kenyan presidency in 2013.
NOTE: PS Iringo was not on the crashed helicopter flight. He is safe and well in Mombasa