Gunmen in Bahrain have attacked a prison, killing a policeman and freeing inmates convicted of terror offences, officials say.
A security lockdown has been imposed around Jaw prison, south of the capital Manama, the interior ministry said.
It did not say how many prisoners had escaped.
Sporadic unrest has hit Bahrain since protests in February 2011 demanded an end to discrimination of the Shia majority by the Sunni Muslim rulers.
At the time, demonstrators occupied Manama's Pearl Roundabout to press for more democracy.
The protesters were driven out by security forces in March 2011, after the king brought in troops from neighbouring Sunni-led Gulf states to restore order and crush dissent.
The unrest left at least 30 civilians and five policemen dead. Almost 3,000 people were also arrested, and scores were handed long prison terms by military courts.
Opposition activists say dozens of people have been killed in ongoing clashes between protesters and security forces, while bomb attacks blamed on Iran-backed militants have left a number of police officers dead.