News of Chadian President Idriss Deby’s shock death met tributes and condolences as world powers mourned the passing of an ally seen as critical in the fight against security threats in the Sahel region. Deby died from injuries sustained in clashes with rebels, the army said in a surprise announcement Tuesday, plunging a volatile region deeper into crisis. The head of the African Union Moussa Faki Mahamat, a former Chadian prime minister, said he was saddened by Deby’s death, sending his condolences to his family. The announcement came a day after it was announced that Deby, who had been in power for 30 years, was projected to win a sixth consecutive term in elections held earlier this month. Rebels, who have been seeking to oust Deby since 2016, had claimed a number of victories in the past week and clashes were reported in the north of the country at the weekend. Deby’s son, General Mahamat Kaka, will serve as president of the transitional council, according to Agouna. Analysts questioned whether the move was constitutional. The army declared a 14-day period of national mourning and imposed an overnight curfew. Air and land borders would close until further notice.