A woman has been killed and three children wounded when a roadside bomb exploded south of Bahrain's capital, Manama, the interior ministry said in what it called a "terrorist" attack.
The woman was reportedly driving on the opposite side of the highway near al-Eker village on Thursday night when the bomb detonated, causing shrapnel to hit her car.
It was not immediately clear who the bomb targeted, and no one claimed responsibility for the attack.
The police vowed that the "hands of justice would reach those responsible".
READ MORE: Was Bahrain's uprising worth it?
Sporadic violence and bomb attacks largely aimed at Bahraini security forces have become the norm since mass, Shia-led pro-democracy protests were put down by the government in 2011.
In July last year, two policemen in the Shia village of Sitra were killed in a blast that authorities said involved the use of explosives smuggled from Iran.
Tehran denies interference in Bahrain but openly supports opposition groups seeking greater rights for the Shia majority.
Tensions have increased in the Gulf island country in recent weeks after the closure of the main opposition party, Al-Wefaq, the detention of a leading rights activist, Nabeel Rajab, and the revoking of citizenship of Ayatollah Sheikh Isa Qassim, the country's top Shia religious figure.