After opposition leader Raila Odinga organized anti-government protests, a mosque and a church were set on fire in Kibra on Monday night.
Following some protests in the area addressed by opposition leaders on the second day of widespread protests against the expensive living costs and a victory Odinga claims stolen from him in the election last year, fighting between two rival gangs intensified.
"Religious sites must be excluded from this because what is occurring is so inappropriate", a resident stated.
County fire engines were able to put out the fire before it spread to any homes, according to Nairobi Governor Johnson Sakaja.
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After a brief initial delay, three trucks could get to the location, and the fire was stopped from spreading to other homes, Sakaja tweeted.
The battle in Kibra continued for hours, drawing considerable outrage on social media and calls for intervention from Kenyan lawmakers and citizens.
"Just like in Northlands, the police disregard requests to act in Kibra where outsiders brandishing pangas have been mobilized to attack natives. To incite residents against one another, they set a church on fire. We urge our people to show the greatest restraint," said ODM Secretary General Edwin Sifuna, the city's Senator.
Authorities didn't immediately report or confirm any casualties.
Chaos characterized Monday's protests, especially in Kisumu, where villagers forbidden from marching into town engaged in a violent altercation with police, resulting in at least one person being shot dead.
Animals were wiped out, trees were down, and others were set ablaze during an invasion at a sizable farm owned by the family of the late former president Uhuru Kenyatta in Nairobi.
Similar violence was used against Odinga's East Africa Spectre Limited, a gas firm destroyed after being stoned by armed thugs.
In either event, authorities have not made any statements.