The Indonesian health ministry says bird flu is suspected in the recent deaths of a man and his two daughters near Jakarta.
The victims would be Indonesia's first human fatalities linked to avian influenza.
Health Minister Siti Fadillah Supari says there is no evidence the man and his daughters had contact with sickened poultry, which raises the probability of human-to-human transmission of bird flu.
Hundreds of millions of birds have died or been culled across Asia during the past two years due to the deadly virus which has jumped to humans, killing people in Vietnam, Cambodia and Thailand.
World health officials have long feared the virus might change into a form easily transferable among people, triggering a deadly global pandemic.
Some information for this report provided by Reuters and AP.