Yemeni troops clashed with armed tribesmen blocking repairs to the country’s main oil pipeline on Friday and one army officer and a tribal fighter were killed, a local official said.

Tribesmen bombed Yemen’s main oil pipeline in Maarib province last month, halting oil flows to the Ras Isa oil terminal on the Red Sea.

“Armed tribesmen prevented repair teams from fixing the oil pipeline and army forces clashed with them. An army colonel and a tribesman were killed in the fighting which is still ongoing,” the official told Reuters.