Saudi authorities have blamed militants linked to Al-Qaeda for an unprecedented attack that killed Shiite worshippers and stoked sectarian tensions in the Sunni-dominated kingdom.
Masked gunmen in Saudi Arabia's east late on Monday killed at least six Shiites, including children, as they celebrated Ashura, one of the holiest festivals of their faith.
Interior Ministry spokesman General Mansur al-Turki told Saudi media the attackers were "followers of the deviant ideology", using a term often used to describe Al-Qaeda.
The day after the attack two Saudi policemen and two suspects allegedly linked to the incident died in a shootout in Qassim region, north of the capital Riyadh.
Officers rounded up 15 suspects in several cities after the initial shooting in the Shiite-populated and oil-rich Eastern Province.
Radical Sunni groups consider Shiites heretics and have targeted them elsewhere in the region, including attacks that killed more than 40 people in Baghdad in the 48 hours preceding the peak of Ashura on Tuesday.
The Ashura commemorations marked the killing of Imam Hussein, the grandson of the Prophet Mohammed, by the army of the Caliph Yazid in 680 AD -- an event that lies at the heart of Islam's sectarian divide into Shiite and Sunni sects.
Activists in the region gave AFP the names and ages of seven people they said had been gunned down. Five of them were teenagers, including 15-year-old Mohammed Husain Al-Basrawi, and the youngest victim, Mahdi Eid Al-Musharef, was aged nine.
The activists also named 12 people they said were wounded.
The interior ministry gave a different toll of six dead, up from five reported initially. Police said nine were wounded.
Turki told the Asharq al-Awsat daily that security services had hunted down suspects involved in the "terrorist" attack in six Saudi cities.
Minister sacked after shutting Sunni TV channel
In another sign of tensions linked to the incident, Saudi Arabia's minister of culture and information was sacked after shutting down a television channel known for its anti-Shiite rhetoric.
Abdlaziz Khoja was dismissed by royal decree published by the official SPA news agency, hours after he announced the closure of a privately owned Sunni television channel.
"I had ordered the shutdown of Wesal channel's bureau in Riyadh and banning it from broadcasting in the kingdom," Abdlaziz Khoja wrote on his Twitter account on Tuesday. "It is not even a Saudi channel."
Wesal channel is known for hosting Sunni clerics who frequently criticise the Shiite faith.
"I think the situation will get worse and worse," one Shiite resident of Eastern Province told AFP, concerned by the minister's firing because the Shiite community had been heartened that he acted against the channel.
Protests and sporadic attacks on security forces have occurred in Shiite areas of Eastern Province, where the minority community complains of marginalisation.
Saudi courts began in June 2011 to pass sentence on hundreds of people accused of involvement in bloody Al-Qaeda attacks across the Gulf kingdom from 2003 to 2006.
The government has launched a relentless crackdown on the extremist network, including a campaign of arrests, aimed at wiping out the local Al-Qaeda branch.