Kenya's internal security minister, George Saitoti, has been killed in a police helicopter crash near the capital Nairobi.

Saitoti's deputy, two pilots, and two bodyguards also died. They were heading to Oyugis in western Kenya, when the helicopter came down in a forest. It's not immediately clear what caused the accident. Saitoti was one of the most visible figures in Kenyan politics.

For over a decade, he was a deputy to former President Daniel Arap Moi. He was also planning to stand as a candidate in next year's presidential election.

Rescue workers investigate the helicopter crash site in Ngong Forest in the outskirts of Nairobi, Kenya, June 10, 2012. Six Kenyan government officials, including Internal Security minister Professor George Saitoti and his deputy Orwa Ojode, were killed when a police helicopter crashed early Sunday near Nairobi.