NAIROBI, Kenya (AP) — Police and Red Cross workers are engaged in a rescue operation at a swollen river in northern Kenya after a bus carrying an unknown number of passengers was swept away by floodwaters.

Police say some of the passengers managed to escape just before the bus was submerged while others climbed onto the roof.

It is not clear how many are still trapped inside the bus.

The incident happened just hours after Kenya’s roads agency announced the closure of another section of the same road that was flooded after the Tana River swelled due to continuing heavy rains.

Kenya Red Cross said it had dispatched two rescue boats to “ensure swift and effective response.”

The government had on Monday issued a flood alert to residents of Tana River and Lamu counties after a dam upstream was breached by flooding.