Saudi authorities are intensifying efforts to rescue workers who were held under the rubble of a collapsed conference center in Al-Qassim University.

Prince Faisal bin Bandar bin Abdulaziz, Governor of Qassim region, has been following up the incident, Saudi Press Agency reported on Monday.

Four construction workers were killed when the roof of a building they were working on collapsed on site.

Some 50 workers were at the site at the time of the incident.