Harare: An overloaded ferry capsized on Zimbabwe's Lake Kariba, killing at least 15 people and leaving 27 missing, the national disaster management agency said.

The agency said 77 people were rescued and taken to an island on the lake.

Zimbabwe's Civil Protection Unit said it could confirm 114 adult passengers and five crew members onboard based on ticket sales. It added that there could have been an unknown number of children below ticketing age who were not accounted for.

The boat has a carrying capacity of 90 people, the agency said.

Mutsa Murombedzi, a local member of Parliament, posted a video of what she said were people on shore waving off what appeared to be the ageing ferry at the start of its journey. She said rural communities use the boat to travel along the lake to the town of Kariba.

Zimbabwean state broadcaster ZBC published video of speedboats heading towards what appeared to be an overturned boat, with a helicopter hovering overhead. Earlier, Zimbabwe police said a rescue operation was underway but did not give any other details.