DUBAI (Reuters) - Saudi security forces on Tuesday shot dead a member of an armed group that killed five people in an overnight attack on Shi'ite Muslims marking an important religious anniversary, al-Arabiya television reported.
The late Monday assault on a Shi'ite gathering in al-Ahsa district is likely to test already strained relations between Sunnis and Shi'ites across the Middle East because it coincided with the annual Ashoura commemoration of Shi'ite Islam.
The Dubai-based al-Arabiya said security forces who had been hunting suspects in the al-Ahsa attack clashed with and killed "a wanted man" at a rest area in the al-Qassim province, north-west of the capital Riyadh.
A member of the kingdom's emergency forces also died in the clashes, it said.
A Saudi Interior Ministry spokesman earlier said that six people had been arrested in connection with the attack in al-Dalwah village.
"As a group of citizens was leaving a building ... three masked men opened fire at them with machine guns and pistols," the spokesman was cited as saying by state news agency SPA.
Al-Ahsa is one of Sunni-ruled Saudi Arabia's main centers of minority Shi'ites, who in common with co-religionists around the world are marking Ashoura, a holy day commemorating the death of Prophet Mohammad's grandson Imam Hussein with public ceremonies and processions.
In Riyadh, an official council of top Sunni Muslim scholars condemned the attack as a "vicious assault and a heinous crime whose perpetrators deserve the harshest religious penalties."
There are conflicts that are sectarian or have sectarian undertones in countries across the Middle East, including Syria, Bahrain, Yemen and Iraq.
In Saudi Arabia, seen as the birthplace of Islam, Shi'ism has been regularly decried as heretical in sermons and religious broadcasts. Deep-seated suspicion of Shi'ite power Iran across the Middle East has also fueled animosity.
Since capturing the world's attention this year with a flash assault on Iraq, ultra hardline Sunni militants Islamic State have persecuted religious minorities including Shi'ites, who they believe are infidels who deserve to be killed.
On a Facebook page calling itself "The Revolutionary Movement of Qatif," activists posted a video of a young boy in hospital with a bandaged foot describing the attack with a limp voice. Reuters could not verify the authenticity of the video.
"The prayer had finished. Me, Mahdi, Mohammed and Amer were leaving. We saw him carrying a gun and coming from the side road. Then he shot at Mohammed, Hassan, then me and Mahdi. Then there was more shooting. It finished and later they showed me the shell casings," he said.
An onlooker said: "May God heal you."
Qatif, another center of the Saudi Shi'ite minority alongside Al-Ahsa, has been the focal point of anti-government demonstrations in support of Shi'ites.
A local rights activist said that the victims were mostly young men who were standing at the entrance of a local gathering place, known as a Huseiniya, where the commemorative ceremony was taking place.
"It seems the criminals were in a hurry and opened fire on youngsters at the entrance and fled," Ali al-Bahrani, a local rights activist, told Reuters by telephone.
A local online newspaper, www.hasanews.com/, earlier reported that six people were killed and 12 were wounded, some seriously, in what it called a "terrorist attack" on the ceremonies in the village.
Shi'ites say they face discrimination in seeking educational opportunities or government employment in the majority Sunni state and that they are referred to disparagingly in text books and by some officials and state-funded clerics.
They also complain of curbs on setting up places of worship and marking Shi'ite holidays, and say Qatif and al-Ahsa receive less state funding than Sunni communities of equivalent size.
The Saudi government denies allegations of discrimination.
Reporting by Mostafa Hashem in Cairo; Writing by William Maclean and Sami Aboudi; Editing by Noah Browning and Raissa Kasolowsky