A suicide car bomber struck a school bus in restive southwestern Pakistan on Wednesday, killing at least four children and wounding 38 others, a government official said.

A local deputy commissioner, Yasir Iqbal, said the attack occurred in Khuzdar, a district in Balochistan province, as the bus was transporting children to school in the city.

No group immediately claimed responsibility, though suspicion is likely to fall on ethnic Baloch separatists, who frequently target security forces and civilians in the region.

Pakistan’s Interior Minister Mohsin Naqvi strongly condemned the attack and expressed deep sorrow over the children’s deaths. He called the perpetrators “beasts” who deserve no leniency, saying the enemy had committed an act of “sheer barbarism by targeting innocent children.”

Balochistan has been the scene of along-running insurgency, with an array of separatist groups staging attacks, including the outlawed Balochistan Liberation Army, designated as a terrorist organization by the United States in 2019.

The latest attack came days after a car bombing killed four people near a market in Qillah Abdullah, a city in Balochistan province bordering Afghanistan.

Most of such attacks are claimed by BLA, which Pakistan says enjoyed the backing of neighboring India.

In one of the deadliest such attacks in March, BLA insurgents killed 33 people, mostly soldiers, during anassault on a traincarrying hundreds of passengers in Balochistan.