TEHRAN, Iran — Iranian state media are reporting three staffers in the country’s defense industries have been killed in an explosion in a submarine under construction in the country’s south.

A Saturday report by the Fardanews website said the three technicians were killed when batteries on the vessel exploded.

The explosion took place at a shipbuilding factory about 37 kilometers (23 miles) west of the southern port of Bandar Abbas that overlooks the Strait of Hormuz.

Since 1992, Iran has developed a homegrown defense industry that produces light and heavy weapons ranging from mortars and torpedoes to tanks and submarines.