Tunisia's prime minister says a full investigation is underway following Wednesday's deadly attack on a museum in the capital, Tunis.
Prime Minister Habib Essid says they are holding a number of suspects.
"The operation is underway, we have good leads, honestly speaking, there have been arrests. But we hope that when the operation is completed, we will have final results and we will be ready to give you all the details."
Authorities say they have arrested four people directly linked to the attack, as well as five others with indirect ties to the deadly assault.
Sources say two family members of one of the gunmen are among those being held by Tunisian authorities.
The Islamic State has since claimed responsibility for the attack.
Tunisian officials have not said whether the claim is legitimate.
A pair of gunmen opened fire on tourist buses outside a museum inside the Parliamentary Compound in Tunis on Wednesday, leaving 21 dead, including 20 foreigners.
No Chinese nationals are among the dead.
