Afghan officials say two unidentified gunmen have shot and killed a female polio campaigner and seriously wounded her teenage granddaughter in the southern city of Kandahar.
No group claimed responsibility for the attack that took place in the morning of December 28.
The gunmen fled the scene, but security forces have launched a search operation to find them, a government spokesman said.
Kandahar health officials said the pair were eradication-campaign volunteers, going house to house when they were targeted.
"Today was the last day of the campaign and as the workers were leaving a house, the gunmen opened fire on them and fled," senior health official Abdul Qayum Pukhla told Reuters.
Militants in Afghanistan and neighboring Pakistan accuse antipolio health workers of being spies and say the polio vaccinations are part of a plot to sterilize Muslims.
Despite some violent opposition to vaccination in Afghanistan, its anti-polio campaign has had remarkable success for a nation at war.
The number of polio cases in Afghanistan has fallen from 63 in 1999 to just 14 in 2013.
Only eight new cases have been confirmed this year, compared with 108 in Pakistan.