Police in Bahrain say an attack on a prison in the tiny island nation has killed one police officer and freed prisoners held on terrorism charges.

Bahrain's Interior Ministry said on Twitter that the attack Sunday on Jaw prison had sparked a security lockdown in the area.

The Interior Ministry did not say how many prisoners were freed.

Bahrain, a small island off the coast of Saudi Arabia, hosts the U.S. Navy's 5th Fleet and an under-construction British naval base.

The nation has seen low-level unrest since its Arab Spring protests. The kingdom launched a wide-ranging crackdown on dissent in April.

Jaw prison has held both those facing terror charges and political prisoners.