PESHAWAR, Pakistan (AP) — A helicopter crash due to engine failure has killed six people and injured eight others in Pakistan’s northwest, a local police officer said Saturday.

The chartered flight was transporting employees of Mari Petroleum when it crashed in North Waziristan, Khyber Pakhtunkhwa province, according to police officer Ahmed Khan.

A security official earlier put the death toll at seven and said that three Russians — two pilots and a crew member — were on board. He didn't say if they were among the dead. He spoke on condition of anonymity because he was not authorized to talk to the media.

There were no signs of sabotage to the Mi-8 helicopter. The injured were taken to a military hospital in the town of Thal, according to the official.

“A technical fault occurred in the helicopter while taking off,” the official said. “The tail rotor hit the ground while making an emergency landing and an investigation into the accident has started.”

The crash site, Shewa oil field, is about 200 kilometers (124 miles) southwest of the provincial capital, Peshawar.