Photo: The Canadian Press

Bahrain on Sunday carried out its first executions since an Arab Spring uprising rocked the country in 2011, putting to death three men found guilty of a deadly bomb attack on police.

The executions of the Shiite men drew swift condemnation from human rights groups and sparked intense protests by opponents of the Sunni-ruled government, who see the charges as politically motivated. Activists allege that testimony used against the condemned men was obtained through torture.

Hundreds of demonstrators took to the streets in several predominantly Shiite communities to protest the executions.

The rallies at times turned violent as youth hurled projectiles and petrol bombs while police responded with birdshot and tear gas, witnesses said. The sound of gunfire could be heard into the night. The witnesses spoke on condition of anonymity for fear of retribution.

Bahrain's public prosecution said the death sentences were carried out by firing squad. Photos shared by activists purporting to show the bodies of the men showed a tight grouping of multiple gunshot wounds to the heart.

The executions were the first in the U.S.-allied nation since 2010 and followed a spike in protests in solidarity with the convicted men.

Abbas al-Samea, Sami Mushaima and Ali al-Singace were found guilty in 2015 of killing two Bahraini policemen and an Emirati officer deployed to bolster the country's security forces in a bomb attack the previous year. A court upheld their death sentences last Monday.

Bahrain is a tiny island nation off the coast of Saudi Arabia that hosts the U.S. Navy's 5th Fleet, which patrols the waters around the Arabian Peninsula and is the naval counterweight to nearby Shiite powerhouse Iran.

Government forces crushed the 2011 uprising with help from allies Saudi Arabia and the United Arab Emirates, but the country continues to face low-level unrest led by a majority Shiite population that feels marginalized by the Sunni monarchy.

Hundreds of protesters took to the streets Saturday in solidarity with the condemned men as rumours spread that their executions were imminent.

Nicholas McGeehan, a researcher who monitors Bahrain for Human Rights Watch, called the executions inflammatory and unjust as he urged the kingdom's allies to "publicly and unequivocally condemn these killings." Amnesty International deputy director Samah Hadid called the executions "a deeply regressive step."

Protests and clashes continued Sunday despite a heavy presence of riot police deployed in predominantly Shiite areas. Witnesses said shops were shuttered in Daih, where the 2014 bombing happened. Garbage bins were seen overturned and set alight in the streets.

One police officer was wounded when several people shot at a police patrol in Bani Jamra, west of the capital Manama, the Interior Ministry said.

The Ashtar Brigade, a Shiite militant group that claimed the 2014 police attack and a number of other bombings in Bahrain, took responsibility for the attack on the police officer on social media.