At least two people were killed and dozens more wounded when bombs exploded in two buses on a busy highway in the Kenyan capital Nairobi.
The bombings came just a day after twin attacks in the restive port city of Mombasa, including a grenade attack on a bus, which killed four, and a bombing outside a luxury beach hotel.
Kenya's Disaster Operation Centre said the bus bombings had killed two and wounded 62, with 20 of them in a critical condition - mostly women and children.
Kenya's Vice President William Ruto said in a statement that "security agencies are in pursuit of the perpetrators of this heinous and cowardly act".
There was no immediate claim of responsibility for the attacks, although Kenyan authorities are currently engaged in a major security crackdown on suspected supporters of neighbouring Somalia's al-Qaeda-linked Shebab rebels.
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Kenyan media reports said bombs appeared to have been planted on the buses, while unconfirmed reports said powerful grenades may have been thrown at them from the side of the road.
The buses blew up along the Thika Road highway, an area around 8km northeast of Nairobi's city centre.
An reporter at the scene saw a red passenger bus with a large hole in its side, and with the ripped panels spattered in blood. Kenyan media also showed images of a green bus with its roof and sides buckled by an explosion.
The Nation newspaper said the 45-seater buses were almost full when the blasts occurred.
Both Nairobi and Muslim-majority Mombasa, a port city that is one of the main gateways to east Africa as well as a popular tourist destination, have been hit by sporadic unrest in recent months.
