A drone strike killed two Chadian soldiers at a military camp near the Sudan border before dawn on Friday, officials said.
The attack hit the border town of Tine, killing two people and seriously injuring another, local authorities confirmed.
Officials said it was not immediately clear who carried out the strike or ordered the drone attack.
A Chadian military intelligence source said the drone appeared to have come from neighbouring Sudan.
The source said it was unclear whether General Abdel Fattah al Burhan’s army or the Rapid Support Forces were responsible.
Chad warned it could retaliate if the drone is confirmed to have been launched by Burhan’s army.
Security was tightened, with Abeche air base on high alert and reinforcements sent to Tine.
The incident highlights growing regional risks from Sudan’s war, which has displaced more than 12 million people.
