Also confirming the incident, spokesman of the Ghana National Fire Service, Billy Anaglate, described the incident as "unusual". "Others are tourists. We are trying to save those who are trapped by cutting the trees with chainsaws".
A further 20 people were being treated in hospital, Desmond Owusu Boampong, a local police commander, told Reuters.
According to him, initial reports he received indicated that three had died, and so it came to him as absolute shock after being told the number was 18.More news: Theresa May says she will trigger Brexit next Wednesday
The former President in a Facebook post, on Monday said "I am keeping the families of the Kintampo falls victims in mind and praying for them".
The students and teachers, numbering 63, and a driver were from the Wenchi Methodist Senior High School in the region.
Emergency officials said that the students died when trees, uprooted due to a storm, fell on them while they were swimming in a river near the waterfall.More news: Study Sheds Light On Opioid Use Among Children
Ghana's minister for tourism, Catherine Abelema Afeku, said: "We extend our condolences to the families of the dead and pray for the injured".
It's one of Ghana's top tourist draws, and on Sunday, the scene of a freak tragedy.
The Ghana Tourism Authority will work closely with police and Kintampo local officials to ensure the families receive needed support and information, she said.More news: Duterte tells European lawmakers: "Why do you have to f*** with us?"
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