A suicide bomber killed four people when he detonated a car bomb at a police checkpoint in a marketplace in northwest Pakistan on Wednesday, officials said.
Pakistan is grappling with an uptick in militancy since the Taliban returned to power in neighbouring Afghanistan, although the latest attack has not yet been claimed by any group.
Local police official Rasool Daraz told AFP two soldiers, a policeman and a civilian were killed when the bomber blew himself up in Liaqat Bazar of the Datta Khel sub-division of North Waziristan.
"The bomber blew up his vehicle while he was being searched at the check post," he said.
"It seems the bomber wanted to reach another destination but blew himself up after he was stopped by police for a routine search."
Another five people were wounded in the blast.
A second police official, Tariq Dawar, confirmed the incident and casualties.
Officials said on Tuesday six security personnel had been killed in a militant siege on a Hungarian-owned oil and gas exploration site around 70 kilometres (44 miles) northeast of Wednesday's blast.
The attack on Tuesday was claimed by the Pakistan Taliban, a chapter of the Afghan movement that splintered off in 2007 to focus its fight against Islamabad.
On Monday, officials said unidentified militants detonated explosives in two empty girls' schools in North Waziristan, destroying nine classrooms but leaving no casualties.
North Waziristan has historically been a hive of militancy and was the target of a long-running Pakistani military offensive and US drone strikes during the post-9/11 occupation of Afghanistan.
The Pakistan Taliban -- known as Tehreek-e-Taliban Pakistan (TTP) -- is the most active group in the region and mostly focuses its attacks on security forces and foreign interests accused of exploitation.
Since the Taliban returned to Kabul in August 2021, Islamabad has said TTP fighters are plotting their attacks from Afghan soil.