4 people were killed in the Suicide attack on al-Mashhad mosque.

Footage posted on social media shows ambulances rushing to the scene.

Another video shows police and rescue services at the spot of the bombing.

Victims have reportedly been taken to King Khalid Hospital.

The attack occurred during evening prayers. Authorities are investigating the bombing, according to Saudi news website Sabq.org and Russian RT.

This is not the first time mosques have been targeted by bombers in the kingdom.

In mid-October, five people were killed after a gunman opened fire on a Shiite Muslim meeting hall in the Eastern city of Saihat.