Reports said the blasts occurred at five different locations in Manama, and victims were foreigners of Asian origin.
Bahrain is in the grip of political and ethnic unrest, ever since protests started in February 2011 to push for greater democracy and more representation to the majority Shia community in the Sunni-ruled country.
At least 60 people, including several police officers, have been killed, since the mass demonstrations began and the opposition activists have alleged widespread abuse and repression.
Last week, the interior ministry announced a ban on all rallies and public gatherings in the country, further exacerbating the discontent.
The capital Manama was this morning shaken by a series of explosions in Qudhaibiya -- a residential and commercial area, and in Adliya, a posh locality.
"Initial investigations indicate that an Asian man was killed when he kicked a bomb, causing it to explode. He died on the spot," a top official of the Bahrain police was quoted as saying by Gulf News.
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"The second man, also an Asian, was killed when a bomb exploded near Awal Cinema in Qudhaibiya. He died in hospital," the police official said.
He added that a third man, an Asian street cleaner, was seriously injured after a homemade bomb exploded in Adliya.
Though the nationalities of the victims were not known but a bulk of Asian expatriates in the country come from India, besides Pakistan and Bangladesh.
Indians constitute the largest of the expatriate workforce in Bahrain.
Out of nearly 517,000 expatriates, nearly 290,000 are Indian nationals.
"The public prosecution has been informed about the acts of terror and a search for the criminals has been launched," said the police official.
"We urge all nationals and expatriates to keep away from suspicious objects for their own safety and to call the police," he said.
Last month, a security officer was killed in a bomb explosion in a village.