All of those arrested were dissident leaders including five Shias and one Sunni and were picked up overnight and early morning as heavily armed forces and tanks blocked most of the city's thoroughfares.
Opposition leader Hassan Mushaima of the Haq Movement, who had returned last month from self-imposed exile to the UK, was one of the prominent leaders detained as authorities declared that holding of rallies would remain banned.
Abdel Wahhab Hussein from Wafa party and Sunni liberal leader Ibrahim Sharif from the Waad Society were among the six opposition leaders arrested.
"Significant members of the opposition were arrested overnight, including some prominent activists. Soldiers broke into the houses of these figures early in the morning and made these arrests," Al Jazeera reported.
All offices, banks, schools and business establishment remained close for the second day as Bahrain's King Hamad Bin Isa Al Khalifa came under mounting diplomatic pressure to end the crackdown and start negotiations with the dissidents.
The Indian nationals were reported to be safe in the country which has witnessed attacks on some Pakistani and Bangladeshis, an Indian resident told PTI from Manama.
Bahrain has nearly 300,000 Indians, making them the single largest expatriate community in the tiny Gulf country. US President Barack Obama, whose country is a close ally of Bahrain, called King Hamad to express "deep concern" at the bloody crackdown.
British Prime Minister David Cameron has urged the King to pursue "reforms not repression." US Secretary of State Hillary Clinton, now on a visit to countries in the region which have witnessed upheavals, has criticised the deployment in the country, which houses American Navy's 5th fleet.
"What is happening in Bahrain is alarming and it was unfortunately diverting attention and effort away from the political and economic track. That is the only way forward to resolve differences," Clinton said.
Six people, including three policemen, were killed and more than 1,000 others injured in clashes that ensued during yesterday's bloody assault.
The crackdown has angered Shias who comprise 70 per cent of the Kingdom's estimated population of 550,000 and Al Jazeera says that the country's Health Minister Nizar Baharna, a Shia, had announced his resignation to protest against the police bursting into hospitals.
At least 12 Shia judges have also resigned. Bahrain has imposed a three-month emergency rule that gives the military powers to battle the pro-democracy protests that began in mid-Feb.