Thousands of protesters have poured into a main square in Bahrain's capital as the Arab push for change gripped the Gulf.
Security forces have battled demonstrators over two days, leading to the deaths of two protesters.
In a clear sign of concern over the widening crisis, Bahrain's King Hamad bin Isa Al Khalifa made a rare national TV address, offering condolences for the deaths, pledging an investigation into the killings, and promising to push ahead with reforms, which include loosening state controls on the media and internet.
As the crowds surged into Pearl Square in Manama, security forces appeared to hold back.
The move came just hours after a second protester died in clashes with police in the strategic island kingdom, which is home to the US Navy's 5th Fleet.
Opposition groups are calling for greater political freedom and an end to the ruling Sunni monarchy's grip on key decisions and government posts. The nation's majority Shiites have long complained of discrimination.
Many in the square - which was quickly renamed the "Nation's Square" by protesters - waved Bahraini flags and chanted: "No Sunnis, no Shiites. We are all Bahrainis."
Bahrain is one of the most politically volatile nations in the Middle East's wealthiest corner. A prolonged showdown could draw in the region's two biggest rivals: Saudi Arabia, as close allies of Bahrain's Sunni monarchy, and Iran, whose hard-liners have spoken in support of the nation's Shiite majority.
The bloodshed already has brought sharp denunciations from the largest Shiite political bloc, which suspended its participation in parliament, and could threaten the nation's gradual pro-democracy reforms over the past decade.
The second day of turmoil began after police tried to disperse up to 10,000 mourners gathering at a hospital parking lot to begin a funeral procession for Ali Abdulhadi Mushaima, 21, who died in Monday's marches.