Pro-government tribesman and foreign militants clashed in northwestern Pakistan, leaving about 30 dead in fighting that began after an Arab was found shot to death in the area, officials said Tuesday.

The clash between Uzbek militants and local tribesmen broke out in South Waziristan on Monday and continued Tuesday, an intelligence official in the region and a security official said. Both spoke on condition of anonymity because they were unauthorized to make media comments.

Local tribal militants blamed the Arab's shooting death on the Uzbeks, triggering a gunbattle between the two groups near the main town of Wana, the intelligence official said.

At least two children were killed and about 20 injured when a stray mortar round hit their bus.

Security forces have captured two wounded Uzbeks, he said. Central Asians and Arabs suspected of links with al-Qaida are believed to shelter in South Waziristan.

Pakistan's security forces have fought intense battles with foreign militants in the region in the years since the Sept. 11, 2001, attacks in the United States.

A gunbattle between tribesmen and Central Asian militants in South Waziristan last month killed 18 people.