Army officers in Guinea-Bissau announced on Wednesday that they had seized power, just a day before the release of provisional results from a fiercely contested presidential election.

In a statement read on state TV, spokesperson Diniz N’Tchama claimed the takeover was necessary to stop a “destabilisation plan” allegedly driven by local politicians and drug barons seeking to manipulate the vote. The African Union and ECOWAS condemned the coup announcement and demanded the release of arrested electoral officials.

Gunfire erupted earlier in the capital, Bissau, near the electoral commission headquarters, presidential palace and interior ministry, sparking panic among residents. The U.S. mission reported military checkpoints and warned that further gunfire was possible.

The electoral commission had been scheduled to announce results from Sunday’s election between incumbent President Umaro Sissoco Embalo and challenger Domingos Simões Pereira. Both camps had claimed early victory. Embalo’s team accused supporters of opponent Idriarte Dias of trying to block the results, while Pereira insisted Dias was not involved.

Guinea-Bissau, a country of 2 million, has a long history of coups, with at least nine since independence in 1974. Embalo himself claims to have survived multiple attempts. Tensions were already high ahead of the vote, with critics accusing him of overstaying his mandate and allowing the cocaine trade to flourish.

Portugal, the former colonial power, called for calm and urged authorities to resume the vote-counting process immediately.