Tunisia's National Guard were pursuing two suspects in region near Libya's border, when "one of them blew himself up", interior ministry spokesman Khalifa Chibani said.
"They tracked them in the Magroun region near a nature reserve and tried to arrest them but one of them blew himself up,” he added.
“The other suspect was armed with a Kalashnikov assault rifle and opened fire on the police but there were no injuries, the interior ministry spokesman said.
He said the chase was still underway, without giving further details.
Tunisia has faced an insurgency responsible for the deaths of dozens of soldiers, police, civilians and foreign tourists since 2011.
Tunisia has been under a state of emergency since November 2015, when a suicide bombing in Tunis claimed by Daesh killed 12 presidential guards.
