MANAMA // Helicopters flew overhead and Bahraini police fired teargas on Wednesday as they cleared protesters from a central roundabout that has become the main protest site by the island's Shiite majority.
Advancing less than 24 hours after Bahrain declared martial law, police moved in thick lines from Bahrain Financial Harbour, the country's main financial district, to the Pearl Roundabout.
Helicopters buzzed overhead as youths hurled petrol bombs at police and scattered when new rounds of tear gas hit.
Two policemen were killed, a health official said, by protesters who knocked them down as they fled in their cars.
Riot police blocked access to Manama's Salmaniya hospital, where many civilian casualties had previously been treated, and it was difficult to pin down casualty figures. However, Abdel Jalil Khalil, the head of Wefaq, the main opposition party, said at least five protesters have been killed and hundreds wounded in Wednesday's crackdown.
The security operation came a day after Bahrain declared three months of martial law to help quell unrest that has drawn in troops from fellow Sunni-ruled neighbour Saudi Arabia.
It did not appear that Gulf Arab forces invited in by the government for support were involved in the operation.
Thousands of protesters had been camped out at the Pearl Roundabout, near the financial district, during weeks of protests. On Sunday, they overwhelmed police and blocked a main thoroughfare leading to the financial area, crippling the economy. On Wednesday, Bahrain announced it had closed its stock market until further notice.