Mohammed Sharif, district chief of Musa Qala district in Helmand, said today that the bomb ripped through a vehicle the previous night, killing everyone inside.
No one has taken responsibility for the attack but Taliban insurgents fighting Afghan forces routinely target military vehicles with improvised explosive devises throughout the south and east of the country.
Civilian vehicles travelling the same roads often drive over and set off the hidden devises.
Many residents in Helmand say the Taliban rule in much of the countryside, while the government controls the district centers. The militant group has also threatened violence ahead of the country's April 5 presidential election.