Kenya’s police watchdog said Thursday that 20 people had died in custody in the past four months, as protesters clashed with security forces in the capital over a recent death.

Tensions are running high in Kenya, with the public enraged over police brutality in the wake of massive anti-government rallies this time last year.

“We have had 20 deaths in police custody in the last four months,” the Independent Policing Oversight Authority chairman Issak Hassan told the National Assembly.

The statement followed the death in police custody last week of 31-year-old teacher Albert Ojwang, who was arrested for criticising a senior officer online.

Police initially said he had died after hitting his own head against the wall but pathologists told reporters the injuries were “unlikely to be self-inflicted”.

On Thursday, police tear-gassed running groups of protesters, who had rallied over the death.

Rights groups have accused security forces of carrying out dozens of illegal detentions since last year’s protests, with many still missing.