Police on Cyprus used tear gas to break up a crowd that stormed onto the grounds of the presidential palace in Nicosia Tuesday during a protest over a fatal blast at a naval base.

Several hundred demonstrators broke away from a peaceful march in the capital and pushed their way onto the palace grounds.

Thousands of people took part in the protest, demanding that Cypriot President Dimitris Christofias resign after the massive explosion Monday at the Evangelos Floakis Naval Base. Twelve people were killed, including the Cypriot naval commander , and 62 others were wounded. The blast also heavily damaged a power plant, knocking out electricity to nearly half the island.

Authorities say a brush fire near the base set off containers of gunpowder seized from an Iranian ship headed to Syria in 2009.

Protesters accuse the government of criminal negligence, saying officials stored the gunpowder under hazardous conditions instead of destroying it.

A Cypriot government spokesman says officials appealed to the United Nations Security Council to move the explosives elsewhere. But he said U.N. officials took no action.

Cypriot officials say it will take six months to fix the power plant damaged by Monday's blast. Rolling two-hour power cuts are in effect until the repairs are made. The station provides half the island's electricity.