Friday's explosion took place west of the capital, Manama, in a predominantly Shiite village called Karanah.
The explosion, described by the ministry as a "terrorist blast," wounded four policemen as well as a married couple and their child. The statement did not disclose further details on the location or target of the explosion, according to AP.
Last month, a bombing killed two police officers in Sitra, south of Manama.
The tiny Persian Gulf nation of Bahrain has faced unrest for more than four years, sparked by widespread 2011 protests.