Al-Jazeera said Friday its Cairo office was stormed by "gangs of thugs" and burned, the most aggressive attack against the Arab news channel during a period of escalating violence against journalists in the region. The channel also said the government arrested its bureau chief and a reporter.

The arson is one of the most targeted attacks to date on foreign journalists covering the recent turmoil in Egypt and comes after a weeklong attempt by President Hosni Mubarak's regime to crack down on al-Jazeera's coverage of the pro-democracy...