Suspected militants on motorcycles ambushed a vehicle carrying instructors from a private vocational school in northwest Pakistan on Monday, killing four women and wounding the driver before fleeing, police said.

Iran press/ Asia: The attack took place in the village of Epi in Mir Ali, a town in the North Waziristan district in a former tribal region bordering Afghanistan, said Shafi Ullah Khan Gandapur, a district police chief.

Police said the slain women were sent to the village by the Bravo Institute of Technology, Peshawar, under an agreement with the Sabawon Pakistan charity. They had planned to train 140 residents for skilled occupations that would allow them to open their own businesses.

"Is this the way to give back to someone for the hard work they were doing for the poor?" Fayaz Khan, the school's chief executive, told NBC News.

Arfan Ullah Marwat, a spokesman for the Sabawon charity, said the women were not their employees.

Gandapur said the attack might have been avoided if police had received a request for security in an area where militants have stepped up attacks on troops in recent months.

The wounded driver, Abdul Khaliq, said he saw assailants on two motorcycles open fire and then flee. He said he was hired by the Bravo Institute to take the women from the town of Bannu to the town of Mir Ali and back.