Nairobi, Police and Red Cross workers are carrying out a rescue operation on a swollen river in northern Kenya after a bus carrying an unknown number of passengers was swept away by flood waters.

Police say some passengers managed to escape just before the bus sank, while others climbed onto the roof.

It is unclear how many people are still trapped inside the bus.

The incident occurred just hours after Kenya's Roads Agency announced the closure of another section of the same road where the Taan River was flooded due to continuous heavy rains.

The Kenya Red Cross said it had dispatched two rescue boats to "ensure a quick effective response".

The government issued a flood warning for residents of Tana River and Lamu counties on Monday after flooding caused the breach of a dam in the upper reaches of the river.