Three Frenchmen were killed Monday and at least one other was injured when they came under fire while traveling in the Saudi Arabian desert north of Medina, a spokesman for the kingdom's Interior Ministry said. Maj. -Gen. Mansour al-Turki said the group of French travelers were resting on the side of a road when gunmen fired at their car, instantly killing two of the men. The third man died later after he was taken to a hospital, and the four Frenchman was in serious condition at an area hospital, al-Turki said. Women and children also were with the group, who were on a road 17 kilometers (10.6 miles) north of Medina, but they were uninjured. Saudi authorities were investigating the attack, al-Turki said. "Undoubtedly this is a criminal act, but it's too early to determine their motives and whether it is terrorism," he said. The area the group was traveling is restricted for Muslims only. The road were the attack occurred leads to Medina, the birthplace of the Prophet Muhammad. Muslims often visit Medina after performing a pilgrimage to another Saudi Arabian holy city of Mecca. Though al-Turki said it was too early to determine if the attacks were terror-related, Saudi Arabia has been waging a heavy campaign against al-Qaida militants since a wave of suicide attacks on foreigners in the kingdom in 2003.