One of the top commanders in Iran’s ballistic missile program was among those killed Saturday, November 12, in an explosion at a base for the Islamic Revolutionary Guards Corps, the group said in a statement on Monday, according to The New York Times.

The commander, Brig. Gen. Hassan Moghaddam, was killed along with 16 other Revolutionary Guards members at a military site outside Bidganeh, about 25 miles from Tehran. The Revolutionary Guards, Iran’s elite military force, said the explosion was an accident that occurred while soldiers were transporting munitions at what it characterized as a base mostly used as an ammunition depot.

Iranian officials did not explain why General Moghaddam was at the site at the time of the explosion. An exiled Iranian dissident group, the Mujaheddeen Khalq, claimed that the base was mostly used as a center for missile development and storage. But that report could not be confirmed.