Unidentified gunmen shot dead five people in Saudi Arabia's Eastern Province late on Monday evening, the state news agency reported.

Nine people were wounded in the attack in Al-Dalwah town in Al-Ahsa district, a police spokesman was quoted as saying.

"As a group of citizens was leaving a building...three masked men opened fire at them with machine guns and pistols," the spokesman said, adding that the incident was under investigation.

It gave no further details. Al-Ahsa is one of the two main centres of minority Shi'ite Muslims in Sunni-ruled Saudi Arabia, along with the district of Qatif.

Videos purporting to show the aftermath of the attack posted to social media showed a body lying in a pool of blood outside a building, with people milling around calling for help. The authenticity of the videos could not immediately be confirmed.

One of the videos showed a man holding spent bullet casings at the bloodstained entrance to what appears to be a Shi'ite place of worship. – Reuters