At least 16 students are among 25 people killed by a roadside bomb in Logar province to the south of Kabul, the Afghan capital, officials said.

The blast happened on Thursday as a convoy of police were patrolling the district of Mohammad Agha.

Four police officers were among the dead.

A lorry laden with explosives had overturned the previous night and was reportedly detonated by a remote control as policemen arrived to inspect the wreckage.

The children, who were all teenagers on their way to school, were also caught in the blast.

Abdul Hameed Hamid, a district governor, said it was difficult to establish an exact death toll as many of the bodies were torn to pieces.

He said that some people were also wounded by the explosion.

Al Jazeera’s Zeina Khodr, reporting from Afghanistan, said the provincial authorities expected the death toll to rise.

“Logar is still a very dangerous place, it’s approximately 25km south of Kabul, and we know that the Taliban does have strongholds there as well as other groups like Hezb il-Islami,” said said.

No one has so far claimed responsibility for the attack.

Attacks, mostly blamed on the Taliban, have increased across Afghanistan since US marines launched a major offensive last week in the southern Helmand province to drive out the fighters.

The Taliban has vowed to resist the offensive and hit back. – Al Jazeera