MANAMA, Bahrain – Bahrain's leaders banned public gatherings and sent tanks into the streets Thursday, intensifying a crackdown that killed five anti-government protesters, wounded more than 200 and turned a hospital into a cauldron of anguish and rage against the monarchy.

Bahrain's streets were mostly empty after the bloody clampdown, but thousands defied authorities by marching in cities in Libya and Yemen as the wave of political unrest continued in the wake of uprisings that toppled leaders in Egypt and Tunisia.

The tiny kingdom of Bahrain is a key part of Washington's military counterbalance to Iran by hosting the U.S. Navy's 5th Fleet. Bahrain's rulers and their Arab allies depict any sign of unrest among their Shiite populations as a move by neighboring Shiite-majority Iran to expand its clout in the region.

While part of the recent revolt in the Arab world, the underlying tensions in Bahrain are decades old and pit the majority Shiites against the Sunni elite.

After allowing several days of rallies in the capital of Manama by disaffected Shiites, the island nation's Sunni rulers unleashed riot police who stormed a protest encampment in Pearl Square before dawn, firing tear gas, beating demonstrators or blasting them with shotgun sprays of birdshot. Along with two who died in clashes with police Monday, the new killings brought the death toll this week in Bahrain to seven.

The willingness to resort to violence against largely peaceful demonstrators was a sign of how deeply the monarchy fears the repercussions of a prolonged wave of protests.

In the government's first public comment on the crackdown, Foreign Minister Khalid Al Khalifa said it was necessary because the demonstrators were "polarizing the country" and pushing it to the "brink of the sectarian abyss."

Speaking to reporters after an emergency meeting with his Gulf counterparts in Manama to discuss the unrest, he called the violence "regrettable," said the deaths would be investigated and added that authorities chose to clear the square by force at 3 a.m. — when the fewest number of people would be in the square — "to minimize any possibility of casualties."