An armed group that clashed with Tunisian security forces was made up of hardened Islamic extremists apparently preparing to attack tourist sites in Tunisia, according to press reports here. The reports were the first indication from Tunisia, where information is tightly controlled, that the group was not made up simply of "dangerous criminals," as the government had said. Authorities have said that 12 people were killed and 15 arrested in the daylong assault a week ago on a hideout outside Tunis, the capital. Tunisia has been relatively untouched by Islamic extremist violence, despite the Islamic insurgency in Algeria that peaked in the 1990s. But in 2002, a suicide attack on a synagogue on the Tunisian resort island of Djerba killed 21 people, mostly German tourists. Investigators linked the attack to al-Qaida.