"We have arrested two persons from South Delhi and three others have been detained," DCP (South) Ishwar Singh said.
Three separate cases have already been registered by police in connection with the incident which took place at Mehrauli area on Thursday night.
At least six African nationals had sustained injuries in the incidents. Police attributed two of the incidents to a dispute over African nationals playing loud music and other to a scuffle over public drinking.
Envoys of African countries on Thursday had expressed shock over the killing of Oliver, following which India assured them of safety and security of all African nationals.
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The victims in Thursday's cases include two women -- one from Uganda and the other from South Africa -- and at least two Nigerian men who alleged they were abused on racial lines.
While two of the cases have been registered under the charge of criminal intimidation, the other has been registered under charges of causing hurt and wrongful confinement, police had said.
"No African National was seriously injured. A Nigerian national, identified as Leuchy, sustained minor injuries on his nose and he was taken to AIIMS Trauma Centre," police had said.