Pictures shared on social media purport to show people running away from the mosque attack.

Four people were killed and 18 wounded on Friday when a suicide bomber attacked a mosque in Saudi Arabia’s eastern governate of al-Ahsa on Friday, a Saudi interior ministry spokesman said.

Saudi authorities prevented two suicide bombers from entering Imam Rida Mosque in Mahasen neighborhood in al-Ahsa region during Friday prayers, the state-owned Saudi Press Agency (SPA) reported, citing a statement by the ministry’s spokesman.

“When security men stopped them, one blew himself up at the entrance of the mosque and there was an exchange of fire with the other. He was wounded and arrested wearing an explosive belt,” the spokesman said.

Residents said security forces were exchanging gunfire with five suspects.

Eastern regions of Saudi Arabia have been on alert after ISIS claimed two attacks Shia mosques last year.

In August, a suicide bomber killed at least 15 people in an attack on a mosque used by members of a local security force in southwest Saudi Arabia. In May, a suicide bomber blew himself up during Friday prayers at a mosque in the village of al-Qadeeh in eastern Saudi Arabia, killing at least 21 and wounding 81 others.

Related articles across the web

• Female suicide bombers attack Borno town, kill six
• Mapping ISIS attacks around the world
• Mapping ISIS attacks around the world
• Troops Intercept 4 Female Suicide Bombers, Kill 3 In Mafa
• Muslim Cleric Tells Female Suicide Bombers What They'll Get Instead of 72 Virgins... It's Disgusting
• Four female suicide bombers die in Borno attack
• Sniper Has 3 Bullets and 5 ISIS Thugs... What YOU SEE Next Will Make Him a LEGEND
• Your fascination with Muslim women's bodies has a long misogynistic history
• ISIS video shows suicide bomber detonate himself in a crowd near Homs hospital
• A Friend Of The San Bernardino Shooters Is Now Facing Criminal Charges