A suicide bomber exploded himself in the parking lot of a Shiite mosque in the port city of Dammam.

Dammam is located in the oil-rich eastern province where most of the predominantly Sunni kingsdom's Shiites live. The Imam Hussein mosque is the only Shiite mosque in the city.

The bombing occurred during Friday's noon prayers and killed the bomber and three other people. It was the second attack of its kind in one week in this region.

Suicide bomber tried to get into the mosque

Witnesses said that the suicide bomber, a man, was wearing an Abaya, head-to-toe black robe worn by women in Saudi Arabia.

The state-run Saudi Press Agency said security guards halted a car in the parking lot and then the bomber detonated his explosives as they approached, although this detail was contested in other reports.

A worshipper who witnessed the attack told the news agency Associated Press by telephone that the suicide bomber attempted to enter the mosque but was chased by young men, who had set up checkpoints at the entrance. "They chased the suicide bomber when he tried to enter the women's section of the mosque," he said.

'IS' claims responsibility

The Islamic State group claimed responsibility for the attack. IS leader Abu Bakr al-Baghdadi has repeatedly called for attacks on the Saudi kingdom.

A statement posted on a Facebook page used by the extremist group said a "soldier of the caliphate," identified as Abu Jandal al-Jazrawi, blew himself up among "an evil gathering of those filth in front of one of their shrines in Dammam."

Last Friday, an Islamic State suicide bomber killed 21 people in the village of al-Dudeeh, located in the oil-rich eastern Qatif region. It was the deadliest militant assault in the kingdom in more than a decade.

Shiite minority demanding end to sectarianism

Saudi Arabia branded the Islamic State a terrorist group last year and has joined the US-led coalition bombing targets credited to the extremist group in Iraq and Syria.

Witnesses said that members of Saudi's Shiite minority carried out separate protests in Dammam and in the village of al-Qadeeh on Friday evening, demanding an end to sectarianism in the country.

ra/msh (AP, Reuters, AFP)