Yemeni government forces detained 10 al Qaeda-linked fighters on Friday, a security source said, after an attack in a town which underscored the security challenges of next week's presidential elections.
On Wednesday, Islamist militants shot dead a military officer and an election official in the town of Baydah, about 130 km (80 miles) southeast of the capital Sanaa.
The militants opened fire on a car carrying Khaled Waqaa, the leader of a brigade of the elite Republican Guard, killing him as well as the head of Baydah's election committee, Hussein al-Babli, his son and two soldiers. Ten people were wounded.
Yemenis vote on Feb. 21 to pick a leader to replace President Ali Abdullah Saleh, now in the United States for medical treatment, amid concern that violence could reduce turnout.
Militant group Ansar al-Sharia claimed responsibility for Wednesday's attack but said it had targeted only the military commander in revenge for the government's failure to fulfil its half of a deal under which Islamists quit a town they had seized.
Militants agreed last month to pull out of Radda, about 170 km (105 miles) southeast of Sanaa, in exchange for the formation of a council to govern it under Islamic law and the release of several jailed comrades.
The militants' spokesman said that instead of setting up such a council, Republican Guard forces had entered the town. He warned the assassination was just a preliminary response.
Saleh formally handed power to his deputy, Vice President Abd-Rabbu Mansour Hadi in November as part of a Gulf-brokered plan to end months of anti-government protests that paralysed the impoverished state for most of 2011.
Weakened by the upheaval, Yemen's government has lost control of swathes of the country, giving al Qaeda's regional Yemen-based wing room to expand its foothold near oil shipping routes through the Red Sea.