A locally-made sound bomb exploded and a second one was defused in the capital of Bahrain, officials say.
No-one was injured in the blast at around 2130 (1830GMT) in the upscale al-Adliyah district of Manama.
The Interior Ministry said the bomb was made in a steel pipe and left in an empty street. Investigating officers found a second bomb and defused it.
Tensions have risen recently in the Gulf state between the majority Shias and the Sunni-dominated government.
Occasional demonstrations by Shia Muslim youths demanding greater civil rights have led to confrontations with Bahraini security forces.