A female suicide bomber injured 20 people on a busy street in the centre of the Tunisian capital on Monday, authorities said, after a three-year break in attacks in the city.
"It's a tragedy," said Tunisian President Beji Caid Essebsi, during a visit to the German capital Berlin.
"We thought we had eradicated terrorism ...(but it) is still in the heart of capital," he said.
The number of wounded was revised up from nine to 20, including 15 police officers and two teenagers, said police spokesman Walid Ben Hkima, but there were no serious injuries.
Interior ministry spokesman Sofiene Zaag told AFP that the suicide bomber blew herself up in the middle of the day "near police cars" in the upmarket Avenue Habib Bourguiba in Tunis.
Ambulances arrived swiftly at the scene, which was cordoned off by security forces. Shops lowered their shutters and cafes emptied as panic gripped passersby.
An AFP photographer saw the bomber's body, apparently mostly intact, lying on the ground on its back with black glasses on the forehead under one of the neatly-trimmed box trees that line the avenue.
The interior ministry, in a statement, identified the assailant as a 30-year-old woman with no known extremist affiliations, and there was no immediate claim of responsibility.
The ministry said she died instantly.
Police sources said the bomber had most likely not been wearing or carrying an explosive belt, but instead a "home made bomb".
Significant police reinforcements arrived quickly at the scene and at least two people were arrested, the AFP journalist said.
Shortly before the blast, a small group of demonstrators had held a protest in the avenue against the killing near Tunis last week of a teenager by a customs agent.
The attack was the first in the Tunisian capital since November 24, 2015 when a suicide bombing killed 12 security agents on a bus for presidential guards. That attack was claimed by the ISIS.
The Islamist party Ennahdha, the second largest party in parliament, condemned Monday's "cowardly attack" and urged all Tunisians "to unite in confronting terrorism", while reiterating its full support for "military institutions and the police".
Since the 2011 uprising that toppled dictator Zine El Abidine Ben Ali, jihadist attacks in Tunisia have killed dozens of members of the security forces and foreign tourists.
In June 2015, 38 people were killed in a shooting rampage at the coastal resort of Sousse which targeted tourists, while an attack in March that year on the National Bardo Museum in Tunis left 22 people dead, most of them tourists.
The terror attacks claimed by the ISIS devastated Tunisia's crucial tourism sector, which made up seven percent of gross domestic product.
The country has been under a state of emergency since the November 2015 attack on the bus.
The state of emergency was extended earlier this month until November 6, amid a tense political climate ahead of legislative and presidential elections planned for next year.
In March 2016, dozens of jihadists who infiltrated from neighbouring Libya assaulted security posts in the southern region of Ben Guerdane in what Tunisian authorities said was an aborted attempt to declare an "emirate".
The attack, which went unclaimed, left 20 dead among security forces and civilians.
Calm has led to a rebound in the tourism industry over the past two years, with more than six million foreign travellers visiting Tunisia in the first nine months of 2018, according to government data.
Arrivals rose 16.9 percent to 6.3 million in the nine months to the end of September, surpassing the number for the whole of 2014.
Tourism revenues in the first nine months of 2018 totalled just over 1 billion euros ($1.2 billion), a rise of 27.6 percent year-on-year.
Tourism Minister Selma Elloumi Rekik told AFP in May that she expected total arrivals to exceed eight million in 2018, higher than the seven million recorded in 2010, a benchmark year for Tunisian tourism.
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