(CNN) At least 50 people, including seven children, were killed in a bus crash west of Nairobi, Kenya, on Wednesday, police said.

The bus was traveling from the Kenyan capital to the port city of Kisumu when the driver lost control while going down a steep slope, authorities said.

Kericho County Police Commander James Mugera told CNN that authorities believe the driver "lost control of his vehicle," in the predawn hours on the Kisumu -- Muhoroni highway in Fort Ternan, Kericho County, a region north west of Nairobi.

My heartfelt condolences to the families of fellow Kenyans who lost their lives in a tragic road accident at Fort Ternan in Kericho County this morning and wish those in hospital quick recovery. — Uhuru Kenyatta (@UKenyatta) October 10, 2018

President Uhuru Kenyatta posted a message on his Twitter page offering "heartfelt condolences to the families of fellow Kenyans who lost their lives in a tragic road accident at Fort Ternan in Kericho County this morning." He also wished a "quick recovery" for those who were injured in the crash. The injured were taken to local hospitals, the Kenyan Red Cross said.