ISLAMABAD -- A chartered helicopter crashed in Pakistan's northwest Khyber Pakhtunkhwa province on Saturday afternoon, killing six people on board while injuring ten others, police officials said.

The incident happened at about 1:00 pm local time when a helicopter chartered by a private oil exploration and production company Mari Petroleum crashed in the Shewa area of North Waziristan district of the province, District Police Officer Rokhanzeb Khan told Xinhua.

Six people, including two Russian pilots of the aircraft, were killed in the unfortunate incident, said the official, adding that ten others sustained injuries, including staff of the private company.

The incident occurred due to a technical fault in the aircraft immediately after it took off, according to local government officials. The engine of the helicopter caught fire before it hit the ground and crashed, officials added.

The cause of the technical fault is still unknown and is being investigated by the relevant authorities.

Following the incident, rescue teams and security personnel reached the area and cordoned it off.