The aircraft, which had been on a visit to troops deployed in northwest Kenya to combat endemic cattle-rustling, came down just minutes after leaving Cheptulel Boys Secondary School in West Pokot County, Ruto said.
Two soldiers survived the crash and were in hospital, he said, adding that an air investigation team had been sent to discover the cause.
“Our motherland has lost one of her most valiant generals,” Ruto told a news conference. “The demise of General Ogolla is a painful loss to me… A distinguished four-star general has fallen in the course of duty, and service to country.”
Ogolla was previously the head of the Kenyan air force, before rising to deputy military chief and then being promoted by Ruto last year to head the military.
Ogolla joined the Kenya Defence Forces in 1984, where he trained as a fighter pilot with United States Air Force and as an instructor pilot at the Kenya Air Force (KAF), according to a Defence Ministry profile.