Saudi authorities blamed militants linked to Al-Qaeda, and a cabinet minister was sacked Wednesday, after an unprecedented attack that killed Shiite worshippers and highlighted sectarian tensions in the Sunni-dominated kingdom.
The dismissal of Culture and Information Minister Abdlaziz Khoja follows Shiite calls for action against hate speech in the media.
Masked gunmen in the kingdom's east late on Monday killed at least six Shiites, including children, during the celebration of Ashura, one of the holiest occasions of their faith.
The attackers were "followers of the deviant ideology", interior ministry spokesman General Mansur al-Turki told Saudi media, using a term often employed by authorities to describe Al-Qaeda.
Activists in the Shiite-populated and oil-rich region gave AFP the names and ages of seven people they said had been gunned down in Al-Dalwa, a town of several thousand people.
Five of the victims were aged 18 or younger, including 15-year-old Mohammed Husain al-Basrawi, and the youngest to die, Mahdi Eid al-Musharef, 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.
On Wednesday officials including the area's governor, Prince Badr bin Mohammad, visited those recovering from their injuries, the Saudi Press Agency (SPA) reported.
Radical Sunni groups consider Shiites heretics and have targeted them in deadly attacks elsewhere in the region.
The Ashura commemorations mark 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.
A resident of Al-Dalwa said the town is grappling with mixed emotions after the loss of so many: "Anger, sadness, and also afraid for the future."
Thousands -- including some Sunnis -- are expected to attend the victims' burial on Friday, said the resident who asked to remain anonymous.
A royal decree dismissed Khoja hours after the information minister announced the closure of a privately owned Sunni television channel which is known for hosting Sunni clerics critical of the Shiite faith.
The royal decree that fired Khoja, and was published by SPA, did not give specific reasons for his removal but said it came "at his request".
"Thank God I served my religion, my nation and my king for nearly a half century, faithfully and with honour", Khoja tweeted.
In his rare comments on Twitter, he had denounced sectarianism.
"Saudi Arabia is a kingdom of humanity, founded on Islam. Our motto is tolerance, co-existence..." he posted following the shootings.
Residents of Eastern Province had different interpretations of Khoja's removal.
"I think the situation will get worse and worse," one told AFP, concerned by the minister's firing because the Shiite community had been heartened that he acted against the channel.
Another resident had a more positive view, saying his dismissal may have been a message that he had not cracked down hard enough on inflammatory media language.
"And also the government wants to say to the world that 'We acted'," the resident said from Al-Dalwa, asking for anonymity.
Protests and sporadic attacks on security forces have occurred in Shiite areas of Eastern Province, where the minority community complains of marginalisation.
The attack was a "cowardly and heinous crime contradicting Islam and its values", said Abdullatif al-Zayani, secretary general of the six-nation Gulf Cooperation Council.
Two Saudi policemen and two suspects allegedly linked to the incident died in a shootout in Qassim region, north of the capital Riyadh, the day after the attack.
Fifteen other suspects were arrested.