ABC News July 31, 2019

32 people, mostly women and children, killed by roadside bomb in Afghanistan

WATCH: Over 3,000 civilians were killed in Afghanistan in 2018

At least 32 people, mostly women and children, died Wednesday when a roadside bomb ripped through a bus in western Afghanistan.

Fifteen others were wounded, Mohibullah Mohib, a spokesman for the police chief in Farah province, told The Associated Press. Most of those wounded were in critical condition.

(MORE: Report lays bare grim toll of Afghanistan war in first half of 2019)

No one has claimed responsibility for attacking the bus, which was traveling on a highway between the cities of Herat and Kandahar, but Taliban fighters operate in the region and often use roadside bombs, the AP reported.

Wednesday's attack comes a day after a U.N. report was released documenting the nearly 4,000 Afghan civilian casualties in in the first half of 2019 -- 1,366 killed, 2,446 wounded.

(MORE: Trump says he could win war in Afghanistan but doesn't want to kill millions)

The report concluded that most casualties -- about 52% -- continue to be caused by anti-government elements including the Taliban. On-the-ground fighting remained the leading cause of casualties, at about one-third of the total, with improvised explosives, or IEDs, responsible for 28% and airstrikes contributing about 14%.

Hoshang Hashimi/AFP/Getty Images
An Afghan man holds the body of a child killed when a bus hit a roadside bomb on the Kandahar-Herat highway, at a hospital in Herat on July 31, 2019.