PADANNA, India — The aspiring jihadists began leaving here quietly in May, slipping away in twos and threes to avoid suspicion.

By the time their relatives realized they were missing, five families — some with small children — had left their comfortable bungalows and jobs as doctors and businessmen to make the perilous journey to Islamic State-controlled territory in Afghanistan.

Authorities believe 19 adults and three children settled in Nangarhar province, on the mountainous border with Pakistan. Their departure has raised alarms about the Islamic State’s reach in India as well as growing extremism in Kerala, a southern state with deep ties through migrant workers to the Arab Gulf.

Two of the Keralites have been killed by drones in Nangarhar, including one as recently as April 11, family members say. Then, on April 13, American forces dropped a Massive Ordnance Air Blast bomb on a cave complex where militant commanders were believed to be hiding.