Kenya's police chief Joseph Boinnet says that members of his force will be investigated over Wednesday morning's bus crash in which 56 people died, the BBC's Ferdinand Omondi reports.

The owners of the bus company have been arrested, he added.

Giving a press conference in the capital, Nairobi, Mr Boinnet said that the bus was licensed to carry 62 passengers but 71 people were on board. It also did not have a licence to travel at night.

There will be an investigation into whether police deliberately ignored the flouting of the regulations.

The bus travelling from Nairobi, to Kisumu, in the west, veered off the road, police said.

It was overloaded and speeding, a survivor told local media.

Police said the driver lost control and the vehicle plunged down a slope at a notorious accident black spot. The roof was ripped off.