On April 11, Deby won over 79% of the vote.
Former prime minister Albert Pahimi Padacke came in second, while Lydie Beassemda came third.
Chad's president of three decades died of wounds suffered during a visit to front-line troops battling a shadowy rebel group, the military announced Tuesday, just hours after he was declared the victor of an election that would have given him another six years in power.
The provisional results still need to be approved by the Supreme Court after it studies potential legal appeals.
Chadians fed up after 30 years of Deby's rule could also align with the calls for change, he said.
India reports another record daily rise in Covid-19 infections
Total cases reached almost 14.3 million, second only to the United States which has reported more than 31 million infections. Meanwhile, 1,185 people died from COVID-19 since Thursday morning, bringing the death toll to 174,308.
Deby, one of Africa's longest-serving leaders, has successfully put down a string of rebellions since taking power, sometimes with military assistance from France. The force also has worldwide support from France, the US and the European Union.
The shock news came only the day after the 68-year-old career military man was proclaimed the victor of a presidential election that had given him a sixth term in office.
In 2006 N'Djamena breaks diplomatic ties with Khartoum for several months, accusing Sudan of aiding rebels who are seeking to overthrow Deby.
Canada also contributed more than $280 million in developmental assistance to the so-called G5 Sahel, which comprises Burkina Faso, Chad, Mali, Mauritania and Niger.
"What you have [now] is a large number of people who would like to be the president of Chad rather than one unified opposition leader".
Chad's President Idriss Deby Itno, pictured in January 2020 at the G5 Sahel summit in Pau, southwestern France.
He pushed through a new constitution in 2018 that would have allowed him to stay in power until 2033 - even as it re-instated term limits. "That in itself is a coup", he said. "I'd rather die than witness instability in Chad", he said.
Chad's military spokesman, Azem Bermendao Agouna, told the Reuters news agency that army troops killed more than 300 fighters and captured 150 on Saturday in Kanem province, around 300 kilometres (185 miles) from Ndjamena.