Torched buildings were smouldering and shop owners were cleaning up the charred wreckage in central Nairobi on Thursday, after a night of looting and arson followed youth demonstrations in which rights group Amnesty Kenya said 16 people were killed.

Thousands of Kenyans took to the streets on Wednesday, to mark the anniversary of deadly demonstrations a year ago and to protest against the death this month of a blogger held in police custody over a complaint by a senior police official.

More than 60 people were killed in the 2024 demonstrations, led by youth who refer to themselves informally as Gen Z, against a proposed tax hike. This month has seen a number of demonstrations following the death of blogger Albert Ojwang, found to have been beaten in jail.

Wednesday's protests saw police fire tear gas and water cannons to disperse crowds in Nairobi, with isolated clashes also breaking out in other towns. Reuters saw several protesters injured in clashes with police.

Amnesty Kenya's executive director Irungu Houghton told Reuters the 16 who were killed on Wednesday had all died of gunshot wounds, suspected to have been inflicted by police officers.

The police have not given an account of casualties or of any shooting. Police spokesperson Muchiri Nyaga did not immediately respond to a request for comment.

Smoke was billowing from at least 10 torched buildings in downtown Nairobi on Thursday morning.

"Look: everything they burnt. So please government, try talking to the Gen Z. Because that this happened (because) of Gen Z. So the Gen Z, try to sit down and talk with the government," said Ibrahim Hamisi, owner of one of the burnt buildings.

Shopkeeper Josephine Apondi said "thugs" had looted 2-million shillings ($15 500) worth of phones and electronics from her Nairobi shop.

"Things are so tough in our country right now. Sometimes we come morning until evening and we have not sold. And to remember this is something you have invested in for so long," she said.

Kenyan media also reported cases of destruction and looting in 26 other counties where protests took place.

Prosecutors have approved murder charges against six people, including three police officers, in the case of the blogger Ojwang, 31, who died after being arrested as part of an investigation triggered by a complaint by the deputy national police chief, Eliud Lagat.

All six defendants have pleaded not guilty. Reuters has been unable to reach Lagat for comment.