People fought battles with homemade bombs, guns and iron bars in the town, about 400 km (250 miles) southwest of the capital, after rumours circulated that only certain tribes would be offered jobs at the nearby Gafsa phosphate complex.
Army units were on their way to try to halt the fighting and military helicopters were deployed over the town.
"People are scared," Ahmed Achouri, a Metlaoui resident, told Reuters by telephone. "We are in a real war ... we ask for more security."
State-run media had earlier put the death toll at seven but state television later said 11 people had been killed and more than 100 wounded in the violence.
Tunisia triggered what has become known as the Arab Spring when popular protests forced autocratic leader Zine al-Abidine Ben Ali from power in January. Since then the country`s new leaders have struggled to restore stability.
Authorities have lengthened a nightly curfew in Metlaoui, which will now run from 4 p.m. (1400 GMT) until 6 a.m., the TAP state-run news agency reported.
Another Metlaoui resident, Hedi Radaoui, told Reuters security forces had arrested dozens of people and seized guns and knives.
(Uu.S008)
Editor: Priyambodo RH
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