At least 20 people were injured in the Tunisian capital, Tunis, following a woman blowing up herself near police officers on Monday afternoon.
Several ambulances and numerous police reinforcements were on site, according to an AFP journalist.
The explosion was on the central Habib Bourguiba avenue where police were cordoning off the area.
“I was in front of the theatre and heard a huge explosion,” witness Mohamed Ekbal bin Rajib told Reuters.
Tunisia, which is heavily dependent on tourism, has improved security since a series of militant attacks targeting tourists caused the near collapse of the sector three years ago.
In 2015, 21 people were killed during a hostage siege in its national museum, the Bardo in Tunis, and a gunman killed 38 people on a resort beach.
There have been no attacks on that scale since then, but the economy has remained troubled and the authorities worry about militants who shelter in neighboring Libya.