Chad's President, Idriss Deby has died, an army spokesman said on Tuesday, Reuters reports.
Details of his death are still sketchy but the army authorities said he died from injuries sustained on the front.
The Chadian army is currently combating rebel forces who have launched an assault on the capital, N’Djamena.
His death came a few hours after he won a sixth term in office.
Chad's veteran president, Deby, won a sixth term, provisional election results showed on Monday, as the army said it had beaten back a column of insurgents advancing on the capital, N'Djamena.
The 68-year-old Deby, who came to power in a rebellion in 1990, took 79.3% of the vote in the April 11 election, which was boycotted by top opposition leaders.
He was expected to give a victory speech to supporters, but his campaign director, Mahamat Zen Bada, said he had instead gone to visit Chadian soldiers on the front lines.
"The candidate would have liked to have been here to celebrate ... but right now, he is alongside our valiant defence and security forces to fight the terrorists threatening our territory," Zen Bada told reporters.
The rebel group Front for Change and Concord in Chad (FACT), which is based across the northern frontier with Libya, attacked a border post on election day and then advanced hundreds of kilometres (miles) south.
But it suffered a setback over the weekend. Chad's military spokesman, Azem Bermendao Agouna, told Reuters that army troops killed more than 300 insurgents and captured 150 on Saturday in Kanem province, around 300 km (185 miles) from N'Djamena.