Anti-government protests took place there in 2011 and 2012.Citizen Lab says the software was disguised as a copy of a mobile phone news application called Qatif Today.
The clash with protesters in Qatif, located in a heavily Shiite region, underscored longstanding tensions in Saudi society: there is a sense among the Shiite minority that it is discriminated against by a government practicing a zealous form of Sunni orthodoxy.
Another resident in Qatif who watched the march, Abdulwahab al-Oraid, said it was not clear why the police opened fire at what appeared to be a peaceful demonstration that started with 100 people and later grew to about 300.
It added that the protesters waved Bahraini flags and held marches in two cities in the province of Qatif.
In another video posted by the Facebook group, the crackling sound of gunfire can be heard as a small group of men run for cover down an alley near a central intersection said to be in Qatif.
Though spared the Arab Spring's revolutionary unrest, Saudi Arabia has dealt swiftly with what few protests have been carried out, mostly in the Shiite-dominated eastern Qatif region.
In a new wrinkle, Saudi Arabia, which intervened in April in Bahrain's protests, saw demonstrations last week among its own restive Shiite minority in the oil-rich eastern region of Qatif.
Witnesses described the small protest march in the eastern city of Qatif as peaceful, but an Interior Ministry spokesman said demonstrators had attacked the police before the officers began firing, Reuters reported.
Though spared the Arab Spring's revolutionary unrest, Saudi Arabia has dealt swiftly with what few protests have been mounted, mostly in the Shiite-dominated eastern Qatif region.
The demonstrations followed the death of another man on Thursday in clashes with the police on a central avenue in Qatif.
But in Saudi Arabia, the principle appears to apply to rape victims who have the temerity to appeal, after they have been convicted along with their aggressors.Last year a 19-year-old woman in the eastern town of Qatif appealed against a sentence of 90 lashes for the crime of khulwa (seclusion) with a man who was not related to her.
