The two were killed when regime forces supported by armed vehicles stormed their house the town of Awamiyah. The town has been the scene of violent clashes between anti-regime protesters and Saudi forces for three years.
Witnesses said the two were harshly beaten by the regime forces and taken to hospital, where they died.
The move is considered as part of a fresh crackdown on anti-regime protests in Saudi Arabia.
On Wednesday, a Saudi court in Qatif sentenced seven people to jail terms of up to 20 years for taking part in protests in Qatif.
The men were also convicted of chanting slogans against the government.
Human rights groups have censured the verdicts and called on Saudi authorities to release the detainees.
Activists say there are over 30,000 political prisoners in Saudi Arabia.
In October 2013, rights group Amnesty International censured Saudi authorities for not addressing the “dire human rights situation” in the kingdom.
The group has also handed in a paper to the United Nations, which included information regarding a “new wave of repression against civil society, which has taken place over the last two years.”
SHI/SHI