Five people were killed Saturday when a roadside bomb exploded in an area of northwestern Pakistan rocked by a violent campaign for Islamic law, security officials said. The bomb, planted near a bridge in the scenic Swat valley, went off when it was hit by a car, killing the driver and four others, one security official said. “It was a powerful blast, the car was badly damaged,” said another official. Only two bodies have been identified so far, he said. One was a government contractor engaged in a development project. Pakistani troops last year launched a major offensive against Islamic militants in the once-popular tourist site, home to Pakistan's only ski resort. The mountainous, snow-capped Swat region, renowned for its ancient Buddhist relics, used to attract large numbers of foreign and local tourists. But the valley has been turned into a battleground since radical cleric Maulana Fazlullah, who has links to Pakistan's Taleban movement, launched a violent campaign for the introduction of Islamic Shariah law. Meanwhile, two children and three militants were killed when Pakistani troops shelled suspected Taleban and Al-Qaeda hideouts in a lawless tribal region bordering Afghanistan, officials said Saturday. Troops pounded a suspected hideout and killed three Afghan militants who were planning attacks on security forces in Khar, the main town in Pakistan's northwestern Bajaur tribal district, local official Haseeb Khan said. One mortar shell landed in a house near Khar, killing two children and wounding five other family members, he said. The shelling of suspected bases started overnight and continued into Saturday morning, officials said. Pakistani security forces have been engaged in fierce fighting with rebels in Bajaur since the launch of an army operation there in August. The military says more than 1,500 rebels have been killed and hundreds more have been captured since then. Pakistan's northwestern tribal belt became a stronghold for hundreds of extremists who fled Afghanistan after the US-led invasion toppled the hardline Taleban regime in late 2001.