Police immediately blamed the assault on Taliban fighters although there were no claims of responsibility.
Witnesses said a group of about 30 fighters stopped three NGO vehicles in Spin Kotal village in Kandahar province.
They fired on one car, killing the driver and wounding another occupant, witness Beryali Khan, a member of the constitutional commission in the province of Uruzgan, said.
The name of the NGO for which the victims worked could not immediately be confirmed.
Taliban leader Mullah Omar has
resurfaced in recent months
Kandahar police chief Mohammad Akram Khakreezwal said large numbers of men had been sent after the attackers.
The attack occurred near the site of the killing in April of an El Salvadorean working for the International Committee of the Red Cross.
It comes a few days after six Afghan policemen were killed in an ambush in southern Helmand province.
Today's attack also follows word from an official of the Taliban that its leader Mullah Mohammad Omar appointed a new deputy commander for the south on Saturday.
Mullah Omar is rumoured to have given him orders to step up attacks on US-led coalition troops and government targets.