Two men were shot dead and two others wounded on Wednesday when Saudi security forces stormed a house to arrest a wanted man in Awamiya village in the troubled Qatif area, the scene of protests by minority Shia Muslims.
The authorities were trying to arrest one of 23 men the government said were wanted for stirring unrest in Qatif, where 15 people have been killed since November in clashes and protests.
"He and his companions opened fire on the security forces and, in dealing with the situation as it required, it resulted in the death of the wanted man ... and one of his companions, and the wounding of two others and the arrest of a third," Saudi Press Agency reported late on Wednesday, citing the government security spokesman.
The wanted man was identified as Khaled Abdulkarim Hassan al-Labad.
Activists in the Awamiya village of Qatif, a focal point for Shia unrest in Saudi Arabia, said a third man was killed in a car and distributed photographs showing wounds in his neck. The photographs could not be independently verified.
Shias began demonstrations to protest what they perceived as systematic discrimination in the Sunni-dominated country. But Shia activities say the rallies have been fuelled by the 15 deaths in Qatif, arrests of protesters and a heavy security presence.
Activists say some of those killed were shot during peaceful protests.
Authorities in Saudi Arabia say they do not discriminate against Shias and say the deaths have all been the result of exchanges of fire after security forces were shot at. One of those killed was a security official.
"The security forces will not hesitate to pursue wanted people and troublemakers on the ground and to arrest them," the spokesman said.
An activist living in the area said security forces had cut street lighting in Awamiya and that there had been unrest in two other parts of Qatif.
Saudi Shias complain members of their community are not appointed to local positions of importance, that their places of worship are sometimes torn down, and that their young people struggle to get government jobs.
They also say the government should stop state-employed Sunni clerics from deriding them in public as heretics.
The authorities have repeatedly denied accusations of discrimination and point to King Abdullah's move to include Shias in a "national dialogue" he started in 2005, and to appoint three of them to the Shura Council, which advises the government on policy.