ACCRA, Ghana — The head of Ghana’s election commission has announced that incumbent President John Dramani Mahama won the country’s presidential election with 50.7 percent of the vote.

Election commission chairman Kwadwo Afari-Gyan said Sunday that opposition leader Nana Akufo-Addo came in second with 47.74 percent of the vote, according to provisional results from Friday’s election.

Armored tanks surrounded Ghana’s electoral commission and police barricaded the road around the electoral offices as the results were announced. Earlier Sunday, police dispersed protesters with tear gas. Protesters wanted the electoral body to delay announcing results until allegations of vote-rigging have been investigated.

Ghana has one of the longest traditions of democracy in this troubled corner of Africa, but Friday’s election was fraught after biometric machines used to ID voters failed in scores of polling stations.