At least 18 civilians were killed and six others have been wounded when their vehicle struck a roadside bomb in Afghanistan's southern Helmand province, a local official told Al Jazeera.
Women and children were among the casualties of the deadly incident on Saturday, according to a provincial government spokesman, Omar Zhwak.
He said that the minivan was travelling in the Marjah district of the province at around 1300 GMT when it struck the bomb.
No one has claimed responsibility for the incident. But in recent weeks, the armed group Taliban had carried out attacks across the country since late April.
Marjah resident Barri Dad told the Reuters news agency that he had lost more than a dozen members of his family in Saturday's blast.
"Those who were killed in this incident were my family members including my nephews, my niece and my brothers' wives," he said.
A witness said all of the dead children he saw at the scene were under the age of five.
Al Jazeera's Jennifer Glasse, reporting from Kabul, said roadside bombs were one of the biggest causes of civilian deaths in Afghanistan.
"The fighting in Helmund has been terrible for over a year now," our correspondent said.
Marjah in Taliban-infested Helmand was the focus of a major US-led military offensive designed to clear out the armed group in early 2010.
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The surge in attacks has taken a heavy toll on civilians, according to the UN mission in Afghanistan.
Almost 1,000 civilians were killed during the first four months of this year, a sharp jump from the same period last year, it said.
Afghan authorities have repeatedly tried to jumpstart talks with the Taliban in the hope of ending the 13-year conflict, but the militants have set tough conditions, including the withdrawal of all foreign troops in Afghanistan.
NATO's combat mission formally ended in December but a small follow-up foreign force of about 12,500 mainly US troops has stayed on to train and support local security personnel.
President Ashraf Ghani's government has drawn criticism for failing to end growing attacks, which critics partly blame on political infighting and a lengthy delay in appointing a candidate for the crucial post of defence minister.
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Ghani last month nominated Mohammad Masoom Stanekzai, a top official in the government body overseeing the country's peace process, for the job.
The post had been left vacant for months due to disagreements between Ghani and his chief executive and former presidential election rival, Abdullah Abdullah.
The Afghan government and the US-led international coalition fighting the Taliban are also keeping a wary eye on the Islamic State of Iraq and the Levant (ISIL), which has grabbed large swathes of Syria and Iraq in a brutal offensive.
ISIL is in an "initial exploratory phase" in Afghanistan, the US Pentagon said in a recent report to Congress, noting the Taliban retained its resilience in the war-torn country.
On Tuesday the Taliban warned ISIL's leader against waging a parallel insurgency in Afghanistan, after a string of defections and reported clashes with fighters loyal to ISIL.
Source: Al Jazeera and agencies