At least 15 people died and 27 remain missing after an overcrowded ferry on Zimbabwe's Lake Kariba capsized on Tuesday, authorities said on Wednesday.

The boat overturned after hitting strong waves.

According to Zimbabwe's Civil Protection Unit (CPU), the boat was carrying 114 adult passengers, five crew members and some children, despite having a capacity of 90 people.

Rescue teams were deployed to search for the remaining passengers.

Video released by Zimbabwe's state broadcaster ZBC showed speedboats heading towards what appeared to be the overturned vessel, while a helicopter flew overhead. An underwater search-and-rescue team was also deployed as emergency crews scoured the vast lake.

Lake Kariba lies along the border between Zimbabwe and Zambia and is one of Africa's largest reservoirs.

With input from local media.