At least 24 people have been killed in five separate attacks across west, east and north Afghanistan, officials say.
Casualty figures for April suggest that about 182 people have been killed in violence in Afghanistan this month, making it the bloodiest of 2013.
Some of the worst incidents took place in the west, where seven people were killed and three injured after a roadside bomb hit a civilian truck.
Afghan police have blamed the Taliban for the attack in Herat province.
The civilians were travelling to the town of Shindand when their vehicle was hit by an improvised explosive device on Wednesday morning.
Women and children were among the casualties, provincial government spokesman Mohidin Noori said.
"It was the work of enemies of Afghanistan, the terrorists," he added, referring to the Taliban.
This is the second incident of its type in as many days after a roadside bomb hit a tractor in Zabul province on Monday, killing seven civilians.
In other violence:
- In the eastern province of Ghazni, a roadside bomb killed five government security force men guarding a convoy of trucks in Qarabagh district
- In Laghman province, insurgents attacked a checkpoint, killing four policemen
- In Jowzjan province, police blamed the Taliban for killing six Afghan soldiers whose bodies were found on a main highway
- In Jowzjan province on Tuesday, two health workers were killed in crossfire between insurgents and the security forces
- A bomb in Kabul was planted in a rubbish bin near parliament, causing panic but no casualties
The interior minister has condemned the violence and offered condolences to the families of the victims.