Chad’s President Idriss Déby has died of his injuries following clashes with rebels in the north of the country at the weekend, the army has said.
The announcement came a day after provisional election results projected he would win a sixth term in office.
The government and parliament have been dissolved. A curfew has also been imposed and the borders have been shut.
Mr Déby, 68, spent three decades in power and was one of Africa’s longest-serving leaders.
An army officer by training, he came to power in 1990 through an armed uprising. He was a long-time ally of France and other Western powers in the battle against jihadist groups in the Sahel region of Africa.
Mr Déby “breathed his last defending the sovereign nation on the battlefield”, an army general said on state TV on Tuesday.
He had gone to the front line, several hundred kilometres north of the capital N’Djamena, at the weekend to visit troops battling rebels belonging to a group calling itself Fact (the Front for Change and Concord in Chad).
A military council led by Mr Déby’s son, a 37-year-old four star general, will govern for the next 18 months.
Mahamat Idriss Déby Itno will lead the council but “free and democratic” elections will be held once the transition period is over, the army said in its statement.
Ahead of the election on 11 April, Mr Déby campaigned on a platform of bringing peace and security to the region.
But there has been growing unhappiness over his government’s management of Chad’s oil resources.