Chadian President Idriss Deby has been killed in clashes with rebels, the military said on Tuesday, bringing to an end his three decades in power.
The army said the Chadian leader had been commanding soldiers at the weekend as it fought against rebels who had launched an offensive in northern Chad.
The rebel attack began on the same day as the country's presidential elections on 11 April, in which Deby secured almost 80% of the vote.
Mahamat Mahadi Ali, head of the Change and Concord in Chad (FACT) group, said Deby went to visit the combat zone on Sunday, near to Nokou, about 280 kilometres north of the capital N'Djamena, in the Kanem region, in western Chad, according to live updates from RFI.
Military spokesman General Azem Bermandoa Agouna said Deby had "breathed his last breath" while trying to defend the country on the battlefield.
On Monday, the army had claimed a "great victory" in its battle against the rebels, saying it had killed 300 fighters, with the loss of five soldiers in its own ranks during eight days of combat.
The government had tried allay fears on Monday that the rebel attack was over. Some residents of N'Djamena were frightened by the sight of tanks deployed in the city, AFP reported.
As part of measures following Deby's death the country's constitution has been suspended and Chad will be ruled by a military council led by Deby's son Mahamat Idriss Deby Itno, for 18 months.
Deby's son had served as an officer in the Chadian army and was until Tuesday morning the head of the presidential guard.
Idriss Deby's latest election victory had never been in doubt, but the campaign was marred by banned demonstrations, arrests and a boycott from the opposition.
The French army is not concerned about the impact of Deby's death, according to RFI's Franck Alexandre, citing military staff saying that the situation is under control.
Deby was seen as a strong ally of France and had earlier this year announced a deployment of Chadian troops to bolster the G5 Sahel force operating in Mali.
N'Djamena is also home to a French military base, which supports France's Operation Barkhane, focused on fighting hardline Islamists insurgents in Mali.
"He was a brave man who didn't want to believe in his own weaknesses until the end," Roland Marchal, an expert on Chad, told RFI. "There's now enormous concern for the Chadian people."