A roadside bomb blew up next to a minibus at an intersection on a major highway in southern Afghanistan on Thursday, killing at least 14 civilians, officials said.

KABUL, Afghanistan — A roadside bomb blew up next to a minibus at an intersection on a major highway in southern Afghanistan on Thursday, killing at least 14 civilians, officials said.

The blast struck the minibus in the Lashkar Gah-Sangin district in Helmand province on the main road running from the city of Kandahar to Herat, said Daoud Ahmadi, a spokesman for the Helmand governor’s office. He said four were wounded in the blast and the dead included women and children.

The bus was taking people to a bazaar, said Ghulam Haidar, who arrived at the scene after learning that two of his brothers had been killed.

Haidar said he took his cousin and a child who was on the bus to a hospital. He learned later the child died.

President Hamid Karzai condemned the bombing as a “bloodthirsty” attack, saying the explosive was “planted by the enemy of the Afghan people.” NATO described the incident as a “despicable attack” aimed at civilians.

Helmand is one of the Taliban’s strongholds in southern Afghanistan. It has been the scene of some of the fiercest fighting in the war and an area where NATO has poured in troops in a bid to quell the insurgency.