Four killed in market explosion in Afghanistan: Officials
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He said the explosion was caused by a "remote-controlled bomb".
Khost health department director Habib Shah Ansari confirmed four people had been killed and said "over a dozen wounded" had been taken to hospitals in the provincial capital of the same name.
The province has come under attack by the Taleban in recent months.
As Ramadan began on May 27, a Taleban car bomber targeted a CIA-funded Afghan militia group, leaving 13 people dead and six injured in Khost.
It was the deadliest Ramadan since the US-led invasion in 2001 with over 200 killed and hundreds wounded, according to an AFP count based on official figures, underscoring the deteriorating security situation.
Afghan security forces have been struggling to beat back a resurgent Taleban, which last month vowed to make Afghanistan a "graveyard" for foreign forces after US President Donald Trump made an open-ended commitment to keep American boots on the ground.
As it searches for a security quick fix, the Afghan government is considering a proposal to train and arm civilians to defend territories where Islamic militants have been driven out.
The plan has sparked concern the local forces could become another thuggish militia and end up terrorising and abusing the people they are supposed to defend.
In Afghanistan, militias - private armies and government-backed armed groups - have a long and chequered history and many Afghans are wary of them.
"The Afghan government's expansion of irregular forces could have enormously dangerous consequences for civilians," said Ms Patricia Gossman, a senior researcher at Human Rights Watch.
