Local Afghan officials said the deadly incident took place in Sayed Abad District of Maidan Wardak Province on Thursday.
A spokesman for Hayatullah Hayat, the provincial governor of Maidan Wardak, said that the casualties were caused after the bomb exploded near a site where children were playing.
The attack comes as Afghan children are bearing the brunt of the ongoing violence in Afghanistan. A recent UN report shows that the death toll among Afghan civilians, especially children, has increased dramatically due to widespread violence in the war-ravaged country.
Separately, at least two civilians were injured after a magnetic bomb attached to a police vehicle went off in a district of the Afghan capital Kabul.
Elsewhere, in the eastern province of Laghman, at least five Afghan policemen were killed after Taliban militants ambushed a convoy of security forces.
Sarhadi Zwak, the spokesman for the Laghman governor, confirmed that the convoy came under fire from a group of heavily- armed militants in Mehtar Lam, the provincial capital on Thursday afternoon.
Also in the early hours of Thursday, a senior police officer and his brother lost their lives after suspected Taliban militants sprayed them with bullets during a security patrol in the troubled southern city of Kandahar.