Security officials in Yemen say 12 people have been killed in ongoing clashes in the northern province of Amran between Shiite tribesmen and ultraconservative Sunnis.
There has long been tension between Salafi Islamists, who are Sunni Muslims, and former Hawthi rebels, who are Shiite Muslims. Nearly 200 people died in fighting last year.
The Hawthis fought a six-year war against former President Ali Abdullah Saleh until a cease-fire was reached in early 2010.
Since Saleh stepped down as president, the Hawthis have aligned with the former president's loyalists to fight the Salafists, who are members of the opposition Islah Party.
Fighting erupted Saturday, a week after a new governor from the Islah Party was installed in Amran. The officials spoke on condition of anonymity in line with regulations.