Another 140 were injured, two of them seriously, provincial governor Rose Mureshyankwano said.
Of those taken to hospital, 17 were kept in for treatment while the rest were discharged.
Local mayor Habitegeko Francois said 14 people died immediately after the lightning strike in Nyaruguru district, while another two later died of their injuries.
Mr Francois said there was a similar incident on Friday, in which a student died after lightning hit a group of 18 people.
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Lightning strikes are frequent across Rwanda, with 18 people killed in different parts of the country last October.
During 2016 – the most recent year with complete figures – lightning killed 30 people and injured 61, according to the country’s ministry of disaster management and refugee affairs.