Additionally, over 500 people are reported to have been arrested and 107 injured when demonstrators and police clashed in the outskirts of the capital Nairobi.
The KNCHR accuses the police of collaborating with criminal gangs that are said to have participated in the violence, allegations that the police deny.
The nationwide demonstrations mark the 35th anniversary of the historic protests in 1990 with demands for free elections.
Monday's clashes are the latest in a series over the past few months between police and mainly young demonstrators who are protesting against corruption, police brutality and Kenya's weak economy.
Since the protests began, over 100 people have been killed.
