A Tunisian man “blew himself” up on Monday during a chase by the police, the Interior Ministry said.
Spokesman Khalifa Chibani told AFP the National Guard had received information concerning “two male suspects” in the southern Ben Guerdane region near Libya.
They tracked them down in the Magroun area, a desert zone near a nature reserve, and tried to arrest them but “one of them blew himself up,” he said.
His companion was shot dead, the Interior Ministry said.
Chibani said both suspects wore explosive vests, and had currency from chaos-wracked Libya, grenades and ammunition.
“It is probable that they were planning to go to Libya,” he told AFP.
He said they could be two extremists sought by authorities over connections to the Jund al-Khilafa group, which has pledged allegiance to the ISIS group.
One of the suspects, he said, was armed with a Kalashnikov assault rifle and had opened fire on the police.
After an exchange of fire, security forces “shot dead the second terrorist”, the interior ministry said, adding that the National Guard and the army were searching the area.
He said an investigation had been opened and would determine if the first suspect who blew himself up had activated his explosives vest or if it blew up in the exchange of fire with the security forces.
Tunisia has been under a state of emergency since November 2015, when a suicide bombing in Tunis claimed by ISIS killed 12 presidential guards.
Monday’s incident comes after a series of deadly operations in 2015 and two years after an ISIS offensive on the town of Ben Guerdane.
Authorities say more than 3,000 Tunisians have left to fight for extremist groups in Syria, Iraq and Libya – and could pose a risk if they return