The blast late Friday was the second in three days in the predominantly Somali Eastleigh neighborhood of Nairobi. No group claimed immediate responsibility for the blast.
Tensions have been high in Kenya, which has sent troops into neighboring Somalia to battle the al-Qaida linked al-Shabaab militant group.
Targets of recent bombings have included Christian churches and Muslim mosques. A grenade attack on a passing minibus in Eastleigh last month sparked a riot in which Somali-owned shops were burned and looted, CNN said.