Officers on Monday evening shot a man in a stand-off with Kibera youths after a confrontation over alleged brutality police meted out on Cord protesters earlier during the day.
The injured man was rushed to a nearby clinic for treatment.
Speaking to Nation, Kilimani OCPD Peter Katam said a group of about 200 youth tried to uproot the railway but officers on patrol stopped them.
Mr Katam said live shots were fired when some of the residents tried to take advantage of the chaos to break into people's houses and loot property.
"Of course we cannot just stand by and let a few criminals take the law into their own hands," he said.
A resident on the scene at Kamukunji grounds told Nation that angry CORD supporters were protesting the use of excessive force by police during the anti-IEBC demos.
Mr Katam says the situation is now under control and people are returning to their houses.