Pakistani security forces on Tuesday killed a notorious Taliban commander who they believed was involved in the murder of four women aid workers in the country’s northwest, the army said.

Militant commander Hassan alias Sajna was killed during a gunfight after soldiers raided a hideout in the village of Mir Ali in North Waziristan district along the Afghan border, the army said.

“Hassan alias Sajna was involved in killing of four women workers yesterday in Mir Ali,” the Pakistan army said in a statement.

“The killed terrorist remained involved in terrorist activities against Security Forces & peaceful civilians including IED attacks, kidnapping for ransom, target killing, extortion and also involved in recruiting terrorists,” it said.

The four women aid workers were ambushed by two gunmen on Monday as they were driving through the village.

Local police chief Shafiullah Gandapur said the aid workers were affiliated with a programme run by a local institute to develop household skills for women.

Attacks have decreased in recent years following a series of military offensives against homegrown and foreign militants in the country’s northwest.

In 2014, the army launched a massive operation to wipe out militant bases in North Waziristan aimed at ending a near decade-long insurgency that cost thousands of lives.

But militant groups are still able to carry out sporadic, isolated assaults.

A recent surge in attacks targeting security forces along the Afghan border has sparked fears that jihadist groups may be regrouping.