The army's crack down on Islamist militant groups in Sinai is the reason they targeted the bus transporting cement factory workers, said a military source on Monday as reported by the state news agency.

The attack that took place in the early hours of Monday left three people dead and 17 wounded in Northern Sinai. The militants have also attempted to attack a police station nearby.

"Tightening the security measures in Sinai left tangible results, which were displayed in the confusion of the terrorist groups, who targeted the workers' bus," the military source told the Middle East News Agency.