MANAMA, Bahrain (AP) - Bahraini authorities crushed a prison riot on Friday, leaving at least 40 injured after they fired stun grenades and tear gas, rights groups said.
Prisoners called their families from inside the prison to alert them to the crackdown, Sayed al-Muhafada of the Bahrain Center for Human Rights said.
The rioting occurred in Bahrain's Dry Dock prison on the island of Muharraq, northeast of the capital, Manama, the group said in a statement, adding that the ward at the center of the revolt houses many anti-government activists and human rights defenders waiting to be tried on terrorism charges.
The Interior Ministry announced that order had been restored following the riots, saying on their official twitter feed that prisoners had tried to "break the doors and police interfered and restored order."
Gulf researcher Nicholas McGeehan of Human Rights Watch called for an investigation into the incident. In a statement to The Associated Press, he said reports of the riot were of utmost concern "given well-documented previous instances of brutality and torture at Dry Dock prison."
Bahrain has seen over two years of unrest linked to the Shiite majority's demands for a greater say in the affairs of the minority Sunni-ruled kingdom. In recent months, security forces have mostly kept protests away from the center of the capital.
The island nation with a native population of more than 550,000 has been gripped by near nonstop turmoil since February 2011, when Shiites inspired by the Arab Spring wave of revolts began the uprising.
At least 60 people have died - activists and Shiite leaders say more than 100 - and prominent opposition and human rights figures have been jailed. The country is home to the U.S. Navy's 5th Fleet, the Pentagon's main base to counter Iran's expanding military presence in the Gulf and protect oil shipping lanes through the Gulf of Hormuz.