NICOSIA, Cyprus — Dozens of containers of gunpowder seized from an Iranian cargo ship exploded on a Cypriot naval base Monday in a massive blast that killed 12 people, wounded 62 and prompted the defence minister and military chief to resign.

A Cypriot official said right after the blast that a brush fire had ignited more than 90 containers confiscated in 2009 from a ship heading from Iran to Syria. The official, who spoke on condition of anonymity due to the sensitivity of the matter, later said that the fire may have started inside one of the containers.

The gunpowder was confiscated after the United Nations said that the Cypriot-flagged M/V Monchegorsk was breaching a ban on Iranian arms exports. Iran has frequently been accused of smuggling arms and munitions through Syria to anti-Israeli militants in Lebanon and the Gaza Strip.

The blast knocked out the island's main power station, causing widespread power cuts throughout the day. The Electricity Authority said the station won't come immediately come back online.

Bodies covered with white sheets lay scattered on a charred hillside near the Evangelos Florakis Naval Base on the Mediterranean island's southern coast, while ambulances ferried the injured to hospitals in Larnaca and Limassol. The bodies of the dead where taken to a morgue at Nicosia hospital in the Cypriot capital.

With criticism mounting over how the material had been handled and stored, Defence Minister Costas Papacostas and the country's top military official, National Guard chief Brig. Gen. Petros Tsalikides, resigned over the incident.

Stefanou said investigators had ruled out sabotage as a cause for the blast, but wouldn't elaborate further. He said experts will be called from abroad to assist police and national guard investigators to determine the exact cause of the explosion.

Greece's National Defence General Staff said it had sent 10 "specialized military and security force personnel" to Cyprus to help with investigations following a Cypriot request.

"The Cyprus Republic had acted according to United Nations Security Council resolutions and in consultation with the world body," government spokesman Stefanos Stefanou said. "The task of guarding the material was assigned to the National Guard."

Cyprus House Speaker Yiannakis Omirou, who visited the scene of the blast, told the Associated Press officials there informed him that all containers had blown up in the explosion.

Stefanou said there was no risk of any further explosions.

Asked about concerns that the base commander had reportedly expressed fears over the safety of the gunpowder's storage area, Stefanou said officials convened a meeting last week at the Defence Ministry to discuss the matter followed by an onsite inspection of the storage area.

He said certain decisions were made but weren't implemented in time to prevent the incident.

Nicos Asprou, the community leader of the village of Mari, about a mile from the base, said the community was unaware that gunpowder had been stored in the base.

Asprou said safety procedures had not been followed, and that storage conditions on the base had proved to be "completely unacceptable."

The blast tore off roof tiles and shattered window panes from many homes and businesses in Mari, where one person was injured, Asprou said.

The government spokesman, Stefanou, said that by Monday afternoon, 50 of the 62 people injured had been treated and released from hospitals. Two of those still hospitalized had suffered serious injuries.

President Dimitris Christofias had asked Tsalikides and Papacostas to remain in their posts until replacements were found.

Stefanou said the government has declared a three-day mourning period with all flags at public buildings flying at half staff.