A suicide attack by an unemployed graduate woman on a busy street in the Tunisian capital this week was an "isolated act", a government minister said on Tuesday.Mna Guebla detonated explosives on Monday near a gathering of police cars in the upmarket Avenue Habib Bourguiba in central Tunis, wounding 15 officers and two teenagers in the first such attack in the city since 2015.Interior Minister Hichem Fourati, whose ministry is on the same street, said Guebla was not on a watch-list of potential extremists "and was not known for her religious background or affiliation.""It was an isolated act, the security services were on the alert, they intervened very quickly," he told AFP.Police sources said the assailant appeared to have used a homemade bomb rather than an explosive belt.Guebla, from the eastern region of Mahdia, was an unemployed business English graduate aged 30, said prosecution spokesperson Sofiene Sliti, who also represents the country's anti-terrorism unit.Her family said that in the three years since she graduated, she had been unable to find a job in that field and had instead occasionally worked as a shepherdess.Eight years since a revolution that toppled longtime dictator Zine El Abidine Ben Ali, Tunisia's economy is stagnant and around a third of young graduates are unemployed.Authorities had not previously identified Guebla as a potential extremist, Sliti told AFP.The prosecution spokesperson said there had not yet been any arrests in connection with Monday's attack. Security beefed up Authorities said nobody was seriously injured in the explosion. Tunis returned to normal on Tuesday apart from a reinforced police presence around the blast site, on a major artery and close to the French embassy.Municipal workers had used high-pressure water hoses to clean the area, where tourists were walking again and cafes had re-opened.Organisers of the Carthage Film Festival, set to begin on Saturday at venues on the same road, said it would go ahead as planned.Since 2011, jihadists have been waging a campaign of attacks targeting Tunisian security forces, particularly in the mountainous region near the Algerian border.But Monday's attack was the first in Tunis since November 2015, when a suicide bombing killed 12 security agents on a bus for presidential guards, a few hundred metres from the site of the latest attack.The 2015 attack was claimed by the Islamic State jihadist group.In June 2015, a student went on a shooting rampage in the coastal resort of Sousse and killed 38 people, including 30 Britons.An attack in March that year on the Bardo National Museum in Tunis left 22 people dead, all but one of them foreign tourists.Those attacks, also claimed by 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 bus attack.The state of emergency was extended this month until November 6, amid a tense political climate ahead of legislative and presidential elections planned for next year.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.