Kenyan Internal Security Minister George Saitoti was killed on Sunday alongside a junior minister and four others after a police helicopter crashed near Nairobi, the vice-president said.
"It is unfortunate that we have lost honourable Prof Saitoti, assistant minister Orwa Ojode," Kalonzo Musyoka told journalists.
Joshua Orwa Ojode was assistant minister for internal security. The other victims included the two pilots and two bodyguards, Musyoka said.
He did not make any comments on the possible cause of the crash.
Saitoti, a candidate in next year's election to succeed President Mwai Kibaki, was the country's longest-serving vice-president.
He was also a key figure in security measures taken in the face of attacks inside Kenya blamed on Al-Qaeda-linked Shebab insurgents who control much of neighbouring Somalia.
Kenya invaded southern Somalia in October after a series of kidnappings and attacks on its territory that it blamed on the Shebab.
The Eurocopter craft took off from Nairobi's Wilson airport and crashed around 8:30 am (0530 GMT) in the Ngong hills near Nairobi.
An AFP journalist on the scene saw six bodies charred beyond recognition being removed from the wreckage of the helicopter that was entirely destroyed.