ADDIS ABABA, March 5 (Xinhua) -- The Ethiopian Electric Power (EEP), the state power utility firm, said Tuesday that a massive power blackout has plunged two regional capitals into darkness. In a press release, EEP said that an interruption in two transmission power lines has caused the power outage in the two regional capitals. The power outage, which began Sunday afternoon, has affected Semera City, the capital of Ethiopia's northeastern Afar region, and Mekelle City, the capital of Ethiopia's northernmost Tigray region. Several other major cities in the country's Amhara, Afar and Tigray regions have also been affected. "There is ongoing activity to quickly repair the damaged power lines," the EEP said.