Officials say the insurgents were trying to plant the IED on a roadside that exploded on them, killing all three on the spot.
The incident took place in Sozyano area of Shah Wali Kot District around 08:30 pm last night.
IEDs planted on public transportation ways claim hundreds of lives every year in Afghanistan.
United Nations Assistance Mission in Afghanistan (UNAMA) stated in an earlier report that there was 16 percent increase in civilian casualties in the first four months of the current year in comparison with the first four months of last year, noting IEDs as the second biggest cause behind the increase.
2,937 civilian casualties have been recorded in these four months out of which there are 974 deaths and 1,963 others are wounded.