At least 13 people died when Shia Muslim fighters clashed with security forces in northern Yemen, local authorities said.
Two soldiers were killed and four others were wounded when the fighters attacked a security checkpoint on Friday, in the northwestern al-Jawf province, according to state news agency Saba.
The fighters were from the Houthi movement, which is seeking to strengthen its hold on the north.
An exchange of fire took place as a result of the attack and three of the Houthi attackers were killed and several others were arrested, a statement by the local authorities said.
The security situation in Yemen is closely watched in Gulf Arab states and the United States, given the impoverished country's strategic position next to top oil exporter Saudi Arabia and to main shipping lanes.
Varying accounts of attack
Security sources told Reuters news agency that violence erupted after members of the Houthi group staged a protest in al Hazm, the provincial capital of al Jawf province, against what they said was the government's failure to boost the economy and end violence.
Officials from both sides have given different accounts of what happened next.
One government security source, who asked not to be named, said armed Houthis exchanged fire with soldiers at an army checkpoint near a local government compound, leaving at least 10 Houthis and three soldiers dead, while another said some of the soldiers may have been supporters of one of the Houthis' long-standing foes, the Sunni Islah party.
The Houthis said they were attacked by armed Islah members supported by a group from the army, according to a statement on a Houthi-linked website, but Islah member Mohammed Qahtan said the group had no armed wing and played no part in Friday's fighting.
Yemen's interim President Abd-Rabbu Mansour Hadi has been struggling to restore order and meet the demands of the country's rival groups since his predecessor, veteran strongman Ali Abdullah Saleh, was forced out of office in 2012.
On Wednesday, the UN Security Council authorised sanctions against anyone in Yemen who obstructs the country's political transition or commits human rights violations but stopped short of blacklisting any specific individuals.