A huge explosion that shook central Kabul on Thursday was an accident in an arms depot, officials said, allaying fears of an attack on the Afghan capital that has often been targeted by militants. "It was an accident, not an enemy act," Lutfullah Mashal, a National Directorate of Security (NDS) official told AFP. "The blast happened in a depot for unexploded ordinance. It was totally an accident. There is no reported casualties but there are some damages."