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DOHA, July 1 (Reuters) - A Bahraini woman died and three children sustained minor injuries when their car was hit by a bomb blast on Thursday that police said was carried out by "terrorists" in southern Bahrain.

Shrapnel hit the car the woman was in, the police said, and security forces were investigating the scene of the attack in the village of East Eker, south of Bahrain's capital, Manama, according to an Interior Ministry statement.

"A terrorist act on Thursday claimed the life of a woman and injured three children who were with her in a car that was hit by shrapnel after a bomb exploded," the director general of Manama's police directorate was quoted as saying by state media.

Sporadic violence and bomb attacks largely aimed at Bahraini security forces have become the norm since mass, Shi'ite-led pro-democracy protests were put down by the government in 2011.

In July, 2015 two policemen in the Shi'ite village of Sitra were killed in a bomb 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 Shi'ite majority.

The human rights record of Bahrain has been criticized by the United States, Britain and rights groups.

On Thursday, seven U.S. senators said in a letter to Secretary of State John Kerry the United States should be prepared to reconsider arms sales, if a recent crackdown on opposition continues.

In June, authorities closed down the main Shi'ite opposition society, detained a prominent rights campaigner Nabeel Rajab and stripped the spiritual leader of the island's Shi'ite Muslim majority of his citizenship.

Bahrain, which hosts the United States' Fifth Fleet, is seen by Sunni-ruled Gulf kingdoms as a strategic bulwark against Iranian influence.

(Reporting by Ahmed Tolba, Writing by Tom Finn; Editing by Bernard Orr) ((Tom.Finn@thomsonreuters.com))