PESHAWAR, Pakistan (AP) — A roadside bomb exploded near a vehicle carrying security forces in restive northwestern Pakistan, killing four officers and wounding five others, officials said Thursday, and the same day two schoolchildren were killed when a mortar exploded near them elsewhere in the northwest.

The roadside bombing happened Wednesday in South Waziristan district, a former stronghold of the Pakistani Taliban, local police officer Dilawar Khan said.

The military in a statement confirmed the “martyrdom” of four officers, but said security forces also responded to the attack and killed five “Khwarij”, a term which is used by the military for the Pakistani Taliban.

In a statement, Interior Minister Mohsin Naqvi paid tribute to the slain officers.

No one immediately claimed responsibility for the attack, but the Pakistani Taliban, known as Tehrik-e-Taliban Pakistan, has stepped up its assaults in the region since its ally the Afghan Taliban seized power in neighboring Afghanistan in 2021.

Later the same day, a mortar fired by insurgents landed near a road in the Tirah valley in the Khyber Pakhtunkhwa province on Wednesday, killing two schoolchildren who were going to school on foot, police said.

The Pakistani military has launched dozens of operations against the Pakistani Taliban and other insurgents in South Waziristan and other former tribal regions nearby, but the militants continue to carry out frequent attacks.

On Thursday, Naqvi met with Chinese ambassador Jiang Zaidong in Islamabad to brief him about an investigation into an attack Tuesday in which a guard shot and wounded two Chinese nationals at a textile mill in the port city of Karachi, allegedly over a private dispute.

China has frequently demanded better security for its nationals who are in Pakistan to work for Beijing’s multibillion-dollar Belt and Road Initiative. An unknown number of Chinese people are also working at factories in the country.