Cyprus police say they have arrested 20 demonstrators who tried to breach gates leading to the island's presidential palace in the capital, Nicosia.

The arrests occurred as thousands of demonstrators filled the streets to protest what they call official negligence in an explosion that killed 12 people Monday at a naval base.

Protesters hurled rocks, flares and fire bombs at riot police, who responded with tear gas. Five police officers were slightly injured.

Many people waved placards calling government officials “criminals” and demanding President Dimitris Christofias resign.

The scale of the mass protest appears to have shocked ministers and embarrassed the Cyprus government.

Meanwhile, funeral services for eight of the 12 dead that included the island's navy chief are being held Wednesday.

Monday's blast also wrecked a key power plant and forced the resignations of the Cyprus defense minister and military chief.