Police spokeswoman Luba Samri says it is not immediately clear what caused today's collision on a highway near the southern town of Lehavim.
Talal al-Krenawi, mayor of the nearby town of Rahat, told Channel 2 TV that the passengers were Bedouin residents of the area returning from a trip to Jerusalem's Al-Aqsa mosque.
Rescue helicopters hovered above the scene, where some 30 ambulances were dispatched to treat the wounded. The windows on the left side of the bus were smashed.