NAIROBI, Oct 10, 2018( Reuters) - At least 50 people were killed in a bus crash between Nairobi and Kenya's western city of Kisumu on Wednesday, police told the Daily Nation, and President Uhuru Kenyatta said authorities were investigating what he called a catastrophic incident. Witnesses said the bus swerved off the road while driving down a steep slope, the newspaper said. Reuters could not immediately reach a police spokesman to confirm the toll. Kenyatta said the authorities were investigating the cause of the accident.