At least three people were killed in a gunfight in the central African country during what authorities said was a failed attempt to overthrow the government.
The government said that a "small group" had been conspiring for more than four months to "destabilize the institutions of the republic."
Security forces, who had been monitoring the individuals, encountered the alleged conspirators late Wednesday near the capital, N'Djamena, sparking a gunfight that left three dead.
Chad's state prosecutor says four officials, including two generals and two lawmakers, were arrested in connection with the plot.
One of the lawmakers was identified as opposition figure Saleh Maki, while the other, Mahamat Kadre, is a member of parliament with the ruling party.
Chad has had a series of coups and rebellions including one led by the current President, Idriss Deby, who seized power in 1990.