Chad's President Idriss Deby Itno died Tuesday from wounds sustained in battle after three decades in power, the army said, opening a period of uncertainty in a country that is a key strategic ally of the West in a troubled region.
His son was immediately named transitional leader as head of a military council and both the government and parliament were dissolved, but the army vowed "free and democratic" elections after an 18-month transitional period.
The shock news of Deby's death came only the day after the 68-year-old career military man was proclaimed the winner of a presidential election that had given him a sixth term in office.
The army also announced a curfew and border closures.
Deby, often called "marshal" due to his military rank, had ruled Chad with an iron fist since taking power on the back of a coup in 1990.
He was nonetheless a key ally in the West's anti-jihadist campaign in the troubled Sahel region, particularly due to Chad's ability to supply weaponry and soldiers.
Former colonial power France hailed Deby as a "courageous friend" and called for a stable, peaceful transition.
Following the announcement of his death on state television, presidential guard officers in civilian clothes roamed the capital N'Djamena with walkie-talkies and handguns.
Police in black uniforms and masks were also deployed, although the military presence was no more intensive than since a rebel offensive began on April 11, the day of the presidential election.
Schools closed and panicked parents sought their children. Government offices also shut.
- 'Defending the nation' -
The army said Deby had been commanding his forces at the weekend as they fought rebels who had launched a major incursion into the north of the oil-producing country on election day.
Deby "has just breathed his last breath defending the sovereign nation on the battlefield," army spokesman General Azem Bermandoa Agouna said in a statement read out on state television.
The army said a military council led by the late president's 37-year-old son Mahamat Idriss Deby Itno, a four-star general, would replace him.
Deby's son oversaw his father's security as head of the elite presidential guard and often appeared alongside him, wearing the force's red beret, dark glasses and military fatigues.
On Monday, the army had claimed a "great victory" in its battle against the rebels from neighbouring Libya, the Front for Change and Concord in Chad (FACT).
FACT, which waged its attacks in the provinces of Tibesti and Kanem, had claimed in a statement that Deby had been wounded -- a report that could not be confirmed.
Ministers and high-ranking military brass had said Monday that Deby was in the region on Saturday and Sunday after the rebel offensive.
Deby was among the world's longest-serving leaders and had on previous occasions gone to the frontlines as government forces battled rebels.
Provisional results released on Monday showed him winning re-election with almost 80 percent of the vote against nine challengers.
His victory had never been in doubt, with a divided opposition, boycott calls, and a campaign in which demonstrations were banned or dispersed.
- Herder's son -
Deby was a herder's son from the Zaghawa ethnic group who took the classic path to power through the army.
He had campaigned for the latest election on a promise of bringing peace and security to the troubled region, but his pledges were undermined by the rebel incursion.
The government had sought Monday to assure concerned residents that the offensive was over, with the army saying it had killed more than 300 rebels and captured 150 more, with the loss of five soldiers.
There had however been no official mention of Deby's wounds.
Panic had been triggered in some areas of the capital N'Djamena on Monday after tanks were seen on main roads, an AFP journalist reported.
They were later withdrawn apart from a perimeter around the president's office.
Government spokesman Cherif Mahamat Zene had said on Twitter that the deployment had been misunderstood, adding: "There is no particular threat to fear."
Several nations including the United States and Britain had neverthless advised their nationals to leave.
Much remains unclear regarding the rebel incursion.
FACT, a group mainly made up of the Saharan Goran people, said Sunday it had "liberated" the Kanem region. Such claims in remote desert combat zones are difficult to verify.
The group has a non-aggression pact with Khalifa Haftar, a military strongman who controls much of Libya's east.
The Union of Resistance Forces (UFR), whose members are mainly from Deby's Zaghawa ethnic group, said Sunday that it supported FACT, but without indicating whether its fighters took part in Saturday's clash.
The Tibesti mountains near the Libyan frontier frequently see fighting between rebels and the army, as well as in the northeast bordering Sudan.
French air strikes were needed to stop an incursion there in February 2019.
In February 2008, a rebel assault reached the gates of the presidential palace before being pushed back with French backing.