Army patrols and tanks locked down the capital of this tiny Gulf kingdom after riot police swinging clubs and firing tear gas smashed into demonstrators, many of them sleeping, in a pre dawn assault on Thursday, that uprooted their protest camp demanding political change.
Medical officials said four people were killed. Hours after the attack on Manama's main Pearl Square, the military announced on state TV that it had "key parts" of the capital under its control and that gatherings were banned.
The developments marked a major crackdown by the island nation's rulers to put an end to days of protests inspired by Egypt's revolt against Hosni Mubarak.
Tiny Bahrain is a pillar of Washington's military framework in the region. It hosts the US Navy's 5th Fleet, which is a critical counterbalance to Iran's efforts to expand its clout in the region.
The capital Manama was effectively shut down on Thursday. For the first time, tanks and military checkpoints were deployed in the streets and army patrols circulated.
The Interior Ministry warned Bahrainis to stay off the streets. Banks and other key institutions did not open, and workers stayed home, unable or afraid to pass through checkpoints to get to their jobs.
Barbed wire and police cars with flashing blue lights encircled Pearl Square, the site of anti government rallies since Monday. Police cleaned up flattened protest tents and trampled banners inside the square, littered with broken glass, tear gas canisters and debris.
A body covered in a white sheet lay in a pool of blood on the side of a road about 20 metres from the landmark square. Demonstrators had been camping out for days around the square's 90 metre monument featuring a giant pearl, making it the nerve centre of the first anti-government protests to reach the Arab Gulf since the uprisings in Tunisia and Egypt.
The protesters' demands have two main objectives: force the ruling Sunni monarchy to give up its control over top government posts and all critical decisions, and address deep grievances held by the country's majority Shiites who claim they face systematic discrimination and are effectively blocked from key roles in public service and the military.
But among Bahrain's rulers, the prospect of a prolonged crisis raised fears of a potential flashpoint between Iran and its Arab rivals in the Gulf. Bahrain's ruling Sunni dynasty is closely allied to Saudi Arabia and the other Arab regimes in the Gulf.
Shiite hard-liners in Iran have often expressed kinship and support for Bahrain's Shiite majority, which accounts for 70% of the island's 500,000 citizens.