SANA'A: Militants emboldened by months of turmoil in Yemen launched a surprise dawn attack Wednesday on a southern city, seizing entire neighborhoods for nearly 12 hours before withdrawing to farmlands on the outskirts, security officials said. They said one soldier was killed and three were wounded in fighting between the militants and government troops in Houta, provincial capital of Lahj province. The militants, believed to number between 150 and 200 and to include Al-Qaeda members, controlled several neighborhoods in the southern part of Houta before they pulled out, the officials said. There was no explanation immediately available for their pullback, but residents reached in the city suggested that the attack could have been meant as a show of force. The attack came a day after a senior US official said Washington was worried that the ongoing unrest in Yemen could fuel connections between Al-Qaeda-linked militants in the country and Al-Shabab insurgents in Somalia. Witnesses in Houta said some of Wednesday's attackers had Somali features and did not speak Arabic. Lahj is home to a refugee camp housing several thousand Somalis who escaped the violence in their country across the Red Sea in the Horn of Africa. Daniel Benjamin, the State Department's counterterrorism coordinator, also said rebels were now operating more in the open and have been able to acquire and hold more territory. The Yemeni security officials also said that bands of militants drove through some neighborhoods in the southern port city of Aden early Wednesday, opening fire on security forces. They had no more details. The officials spoke on condition of anonymity as they were not authorized to talk to the media. Militants, taking advantage of more than four months of political upheaval in Yemen, attacked and seized two other southern cities in Abyan province in late May. In a statement obtained Wednesday, an Al-Qaeda-linked group thought to have been involved the capture of the Abyan cities listed 12 air force and army officers it intended to kill.