Palestinian authorities reported finding bodies in mass graves at a hospital in Khan Younis this week after it was abandoned by Israeli troops
The spokesman added that the passengers include Asian and Arab nationalities, and that the accident happened after a bus crashed.
The accident happened on Hijra road, 170 km from Madinah, near the village of Al-Akhal around 7pm when the privately chartered bus carrying 39 passengers collided with a loader, Arab News reports.
The injured were transferred to Al-Hamna Hospital.
Those on the bus were expats in the kingdom.
Saudi Red Crescent Authority and other emergency services were on the scene to deal with the incident.
An investigation into the collision was underway.