PESHAWAR: Gunmen shot dead four people, including three militants, in a restive Pakistani tribal district near the Afghan border on Wednesday, officials said.

The attack took place in Miramshah, the main town in the troubled North Waziristan district, also known as a stronghold of Taliban and Al-Qaeda-linked militants.

“Several gunmen opened fire on a vehicle in Miramshah Bazaar, killing four people,” a senior security official told AFP.

He said the gunmen also fired rockets at the vehicle, adding “those killed in the attack included three militants and a passer by”.

Another local security official confirmed the incident and casualties.

“We are trying to ascertain to which group the three militants belonged to,” he said.

No one has so far claimed responsibility for the killings.

Officials said the attack may have been triggered by rivalry between different militant groups.

Unknown gunmen killed a senior commander of the Pakistani Taliban, Asmatullah Shaheen, near Miranshah last month.

Shaheen, who was believed to be in his mid-40s and was a former interim chief of Pakistan's Taliban, had a 10-million-rupee ($95,000) bounty payable for his death.

North Waziristan is one of the seven semi-autonomous tribal districts, which Washington has branded the most dangerous place in the world.