The bomb went off in the district of Marja, Mirza Hussain Alizada, a provincial council member from Helmand, told dpa.
Omar Zwak, a spokesman for the provincial governor, said there were 10 casualties and that the exact number of dead was still unclear.
Improvised explosive devices have killed or injured more than 800 civilians - 371 fatalities, 432 wounded - between January and the end of September, according to the latest UN report.
One-third of the victims were children.
At least seven civilians were killed on Sunday after a roadside bomb hit their van in Helmand, according to an official from the southern Afghan province.
