KABUL, Afghanistan — An Afghan provincial official says a bomb hidden inside a cart in a livestock market has killed four civilians in the country's south.

Jawed Faisal, a spokesman for the governor, another 10 were wounded by the blast in the city of Kandahar. It was not clear what the bomb was targeting.

Violence has escalated in recent months, with insurgents trying to take advantage of the transfer of security responsibility from foreign to Afghan forces as the international coalition withdraws from Afghanistan.

As a result, the U.N. says, civilian casualties rose dramatically in the first six months of 2013.