Unidentified gunmen blew up an oil pipeline in Yemen\'s southeastern province of Shabwa on Friday evening, a tribal chief said.Unknown gunmen attacked the oil pipeline with rocket-propelled grenades in Aslaan region, some 150 km east of Ataq, the provincial capital of Shabwa province, the local tribal chief told Xinhua on condition of anonymity.The pipeline links the oil-producing Marib province with the export facilities on the Red Sea, he said.A witness said the explosion caused a huge fire in the region, and firefighters rushed to the scene to extinguish it.The security forces backed by armored vehicles sealed off the region in search of suspects in the pipeline bombing, and it was likely that militants of the al-Qaida in the Arabian Peninsula ( AQAP) were behind the attack, according to a local government official.Shabwa, some 458 km southeast of the Yemeni capital Sanaa, is considered to be another stronghold of hundreds of al-Qaida militants.