At least 15 people were killed and 27 remain missing when an overcrowed ferry on Zimbabwe’s Lake Kariba capsized, authorities said on Wednesday.

The boat, which provides transport between the northern town of Kariba and several islands and fishing camps, overturned on Tuesday after hitting strong waves.

It was carrying 114 adult passengers, five crew members and some children despite a capacity of 90 people, a statement from Zimbabwe’s civil protection unit (CPU) said as the search for the missing continued.

“So far, 77 passengers have been rescued by Matusadonha rescue teams and others,” the CPU said, adding that “15 bodies have also been retrieved”, and two funeral parlours have been engaged to collect the bodies for processing.

About 27 people remain unaccounted for.

A specialised aquatic rescue unit has been airlifted to the area to aid in the search, the CPU added.

Lake Kariba lies on Zimbabwe’s border with Zambia, more than 300 kilometres (185 miles) northeast of the capital Harare.

It is the world’s largest man-made lake by volume.