ISIS has posted a photo of the alleged attacker, whom Tunisian authorities have identified as Saif Al-Deen Al Rezgui, 24, from the town of Gaafour, about 160 kilometers northeast of Sousse, Censor.NET reports citing CNN.
Initial reports Friday about the attack suggested there had been three gunmen, but a Tunisian Interior Ministry spokesman later said the ministry was aware of only one and that he had been killed.
The spokesman, Mohammed Ali Aroui, told CNN on Saturday that the gunman specialized in electronics in pursuing his masters degree and didn't have any known relationship with a terror group.
Tunisian authorities on Saturday began transferring the bodies from Sousse to the capital, Tunis, the Ministry of Health said. It updated the death toll to 38 and said 39 people were wounded.
"The nationalities of the killed, most of them are British, German, and French, this is the 95% of them," according to Prime Minister Habib Essid. "The majority of them are British, then the second in number were German, then third in numbers were French."
Fifteen of the dozens killed were British, and the number may rise, the UK Foreign Office said.
While Tunisian citizens were wounded in the attack, "we affirm that there is no Tunisian (among the dead)," Tunis Prosecutor Sofiene Selliti said, according to TAP.