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 the capital of Manama, security forces appeared to hold back. The dramatic move Tuesday comes just hours after a second protester died in clashes with police in the strategic island kingdom, which is home to the U.S. Navy's 5th Fleet.
Oppositions 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.
Officials at Bahrain's Salmaniya Medical Complex said a 31-year-old man became the second fatality when he died of injuries from birdshot fired during the melee in the hospital's parking lot. The officials spoke on condition of anonymity because they were not allowed to speak to journalists.
After the clash, riot police eventually withdrew and allowed the massive funeral cortege for Mushaima to proceed from the main state-run medical facility in Manama. He was killed Monday during clashes with security forces trying to halt marches to demand greater freedoms and political rights. At least 25 people were injured in the barrage of rubber bullets, birdshot and tear gas, relatives said.
Bahrain's majority Shiites -- about 70 percent of the population -- have long complained of discrimination by the Sunni rulers. A crackdown on perceived dissent last year touched off weeks of riots and clashes in Shiite villages.
The main Shiite opposition group, Al Wefaq, denounced the "bullying tactics and barbaric policies pursued by the security forces" and said it was suspending its participation in parliament, where it holds 18 of the 40 seats.
The declaration falls short of pulling out the group's lawmakers, which would spark a full-scale political crisis. But Al Wefaq warned that it could take more steps if violence persists against marchers staging the first major rallies in the Gulf since uprisings toppled long-ruling regimes in Tunisia and Egypt. A statement from Bahrain's interior minister, Lt. Gen. Rashid bin Abdulla Al Khalifa, expressed "sincere condolences and deep sympathy" to Mushaima's family. He stressed that the death will be investigated and charges would be filed if authorities determined excessive force was used against the protesters.