The violence comes amid tensions ahead of a presidential election set for May and June that could return the Central African state to constitutional rule three years after military authorities seized power.
The violence comes amid tensions ahead of a presidential election set for May and June that could return the Central African state to constitutional rule three years after military authorities seized power.
The headquarters of the opposition Socialist Party Without Borders were cordoned off by security forces after several people were killed in a clash near Chad's internal security agency, the witness said.
However, accounts of the incident given by the government and the party differed.
A government statement said the agency was attacked by representatives of the opposition party, led by its leader Yaya Dillo, resulting in several deaths.
Detailing a separate incident, the government said a member of the party, Ahmed Torabi, had carried out an assassination attempt against the president of the Supreme Court, Samir Adam Annour.
Torabi was arrested, it said.
The opposition party's general secretary said the deaths near the security agency occurred when soldiers opened fire at a group of party members.
He said Torabi had been shot dead on Tuesday and his body was deposited at the agency's headquarters.
On Wednesday morning, party members and Torabi's relatives went to look for his body at the agency and soldiers shot at them, which resulted in multiple deaths, the general secretary said.
He said he was unable to reach Yaya Dillo.
The government said the situation was now under control, adding that perpetrators of the unrest had been arrested or were being sought.
A diplomat said that, for now, the situation appeared contained and focused on the opposition party but they were monitoring the potential for the situation to expose divisions within the security forces.
Internet monitor Netblocks said on X that internet connectivity in Chad was disrupted on Wednesday following reports of an attack on the security agency headquarters.
Chad's Supreme Court in December approved the vote on a new constitution that critics say could help cement the power of junta leader Mahamat Idriss Deby.
His military government is one of several juntas currently ruling in West and Central Africa, where there have been eight coups since 2020, sparking concerns of a democratic backslide in the region.