A homemade bomb planted by "terrorists" has exploded in a Shiite village outside the Bahraini capital, wounding seven policemen on patrol, police said on Thursday.
Among them, one was seriously hurt and two others moderately by the blast in Bani Jamra village on Wednesday night, said Northern Province police chief Ibrahim al-Sheeb.
Sheeb, quoted by BNA state news agency, said an investigation had been launched into the attack, which he blamed on "terrorists."
Bomb attacks are rare in Bahrain, despite frequent clashes between security forces in the Sunni Muslim-ruled kingdom and protesters from its Shiite majority.
The interior ministry said on Twitter that 10 people had been arrested on suspicion of involvement in the explosion.
Witnesses said security forces installed checkpoints at all entries to the village, east of Manama, and stormed some houses in search of suspects.
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US Ambassador Thomas Krajeski condemned the attack, stressing that dialogue is the only path to reconciliation.
"We strongly condemn this attack on police and extend our deepest sympathies to all those injured. All violence is completely unacceptable and unhelpful in efforts to rebuild trust and pursue meaningful reconciliation in Bahrain," he said in a statement posted on the embassy's website.
"It is incumbent upon all segments of Bahraini society to support and participate in the National Dialogue, condemn acts of violence and incitement, and to contribute to a climate conducive for reconciliation."
At least 80 people have been killed in Bahrain since February 2011, according to the International Federation for Human Rights, when Shiite-dominated protests rocked the streets of Manama.
Despite a heavy-handed crackdown in March 2011, backed by Saudi-led Gulf troops, demonstrators were soon back on the street.
A national dialogue was relaunched in February with the aim of resolving the political deadlock in the country.
Strategically located across the Gulf from Shiite Iran, Bahrain is home to the US Navy's Fifth Fleet and is a major offshore financial and services centre for its Arab neighbours in the oil-rich Gulf.