Several people were on Monday night injured during an attack by a group of about 30 youth, suspected to be a criminal gang known as Wakali Kwanza.
The knife-wielding youth attacked people around Naivas Centre and Lake View area of Bamburi, Nyali constituency.
The youth donning bright reflectors were attacking any person on sight, police and locals said.
"They were shouting "Takbir!" before they started slashing anyone in their sight," one of the residents interviewed said.