Saudi security forces clashed with Shiite protesters in the kingdom's oil-rich east, killing one person and wounding three, the interior ministry and witnesses said on Friday.
A "security forces' patrol was carrying out its normal duties in (the Shiite village of) Al-Awamiya late on Thursday when it was attacked with a petrol bomb that left it in flames," said a ministry spokesman in comments published by state news agency SPA.
When security forces "tried to control the fire, they were shot," it said, adding that Saudi forces responded.
"The exchange of fire left two of the assailants wounded. They were taken to the hospital where one of them later died," said the ministry spokesman.
Witnesses said earlier that security forces opened fire with live rounds after protesters hurled stones at one of their vehicles in Al-Awamiya in the Qatif region.
Activists said Issam Mohammed, 22, was killed by multiple bullet wounds.
Three other people were wounded by security force fire, one of them a man driving through a checkpoint at the entrance to the village, the activists said.
Security forces sealed off the village after the clashes, witnesses said.
The clashes came after demonstrations in four Qatif region villages to call for the "release of political detainees, reform and an end to sectarian discrimination," one activist told AFP on condition of anonymity.
Signup to our newsletter and follow us on Facebook and Twitter!
Amnesty International in a statement called for an independent investigation into Mohammed's death.
"This is the latest of several disturbing protester deaths in Saudi Arabia in the last couple of months," said Philip Luther, Amnesty's interim director for the Middle East and North Africa.
"The need to immediately launch an independent investigation into the death... is underlined by the fact that investigations that were announced into previous protester deaths in similar incidents do not appear to have gone anywhere."
Protests erupted in the Eastern Province in March when members of the kingdom's Shiite minority took to the streets to condemn Saudi military intervention against Shiite-led pro-democracy demonstrations in neighbouring Bahrain.
Four Shiites were shot dead in November. The interior ministry said security forces had come under fire from gunmen operating on "foreign orders," in a veiled accusation against Shiite Iran.
A total of 400 people were arrested, of whom around 70 remain in custody, activists say.
Earlier this month, Saudi authorities published a list of 23 suspects wanted in connection with disturbances in Shiite districts of the Eastern Province in recent months.
The interior ministry said those wanted were suspected of "possessing illegal firearms and opening fire on the public and police, in addition to using innocent people as shields."
Other allegations include taking part in "mobs, blocking traffic (and) damaging public and private property," during confrontations between police and protesters.
Most of Saudi Arabia's estimated two million Shiites live in the Eastern Province. They complain of marginalisation in the Sunni-dominated kingdom.