Iran on Wednesday said 18 members of the powerful Revolutionary Guard were killed in an explosion that struck the force's base in the country's west a day earlier.
The state IRNA news agency said 14 other Guard troops were wounded in Tuesday's blast in the city of Khoramabad, some 300 miles (500 kilometers) southwest of the capital, Tehran. The injured were taken to hospitals in Khoramabad.
The report said the blast was caused by a fire that had reached the ammunition storage area, but there was no word on what had ignited the blaze. In their first reports of the blast late Tuesday, most Iranian media said the explosion was an accident.
Although Khoramabad has not seen violence recently, it is geographically close to Kurdish-populated areas that have been the scene in recent months of several attacks by Kurds disgruntled with the central government.
Iran is battling armed militant and separatist movements in the remote southeast along the border with Pakistan and in the far northwest along the border with Iraq.
On Sept. 12, a blast at a military parade in Mahabad, near Iraq, killed 12 people and prompted a cross-border retaliatory raid by Iranian forces. They blamed the attack on Kurdish separatists and followers of former Iraqi dictator Saddam Hussein.
Tehran has accused the U.S. and Britain of provoking ethnic unrest to undermine Iran's security, charges both Washington and London have denied.
The Guard _ Iran's most powerful military force, created after the 1979 Islamic Revolution as an ideological bulwark to defend the clerical rule _ has been at the helm of the government's efforts to battle ethnic and religious insurgencies, as well as opposition groups.
In time, the Guard became a vast military-based conglomerate, amassing a network of economic and political power that extends to virtually every aspect of life in Iran.
The force has been targeted by the latest U.N. sanctions imposed on Iran over it's refusal to halt nuclear enrichment _ a program the West fears could lead to an atomic weapon. Iran denies ambitions to build nuclear weapons, and insists its nuclear program is for peaceful purposes only, such as electricity generation.
The Guard has had large number of casualties in the past.
Last October, a suicide bomber killed at least 42 people, including five senior Guard commanders and more than a dozen other troops, near the Pakistani border in the heartland of a potentially escalating Sunni insurgency. It was the most high-profile strike against the force in the outlaw region of armed tribal groups, drug smugglers and Sunni rebels known as Jundallah, or Soldiers of God.