PADANNA (India) • The silent departure of five Indian families for territory controlled by the Islamic State in Iraq and Syria (ISIS) in Afghanistan has raised alarms about the militant group's reach in India as well as growing extremism in Kerala, a southern state with deep ties through migrant workers to the Arab Gulf. The aspiring militants began leaving here quietly last May, slipping away in twos and threes to avoid suspicion.

By the time their relatives realised they were missing, the five families - some with small children - had left their comfortable bungalows and jobs as doctors and businessmen to make the perilous journey.

The authorities believe 19 adults and three children settled in Nangarhar province, on the mountainous border with Pakistan. Two of the Keralites have been killed by drones in Nangarhar, including one as recently as April 11, family members said. 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.

In the ensuing devastation, 13 Indian nationals were among the 94 who died, the Afghan authorities said, but whether any of the Indian victims were from the Kerala cell has not been determined. Families have hope - a voice message one son sent to his father this week said they had all survived.

Nevertheless, most have accepted they will never see their relatives again. "Let them die in a bombing!" said Mr Abdul Rahman Hamza, 66, the devastated father of a doctor and a school employee who took their pregnant wives and his two-year-old grandson to the remote Afghan region. "What they are doing is not Islamic. The real Islam doesn't promote terrorism."

An estimated 100 Indians have left to fight for ISIS in Syria, Iraq and elsewhere, according to Mr Ajai Sahni, the executive director of the Institute for Conflict Management in New Delhi. This is a fraction of the foreign fighters who have taken up the cause in the past two years.

The terrorist group is considered to be less of a threat to India than other terrorist organisations based in neighbouring Pakistan such as Lashkar-e-Taiba, the group responsible for the siege of Mumbai in 2008, according to Mr Sahni.

Still, there are worrying signs: At least 10 suspected ISIS activists were detained in a six-state sweep last Thursday. And after a suspected militant was killed in a shoot-out with police last month, a pro-ISIS Telegram channel exhorted other Muslims to carry out attacks in India, according to a report from the SITE Intelligence Group. "Kill them, stab them, hit them with a car, use guns, weapons, anything you have. And make them weak, Shed their... blood like water," the message said.

Kerala has long been one of India's most diverse and educated states. But in recent decades, a more extreme form of Islam has taken root, the authorities say, spurred by millions of migrant workers returning from the Middle East.

In the months before they disappeared, Mr Hamza's sons - Ijas Abdul Rahman, 34, a doctor, and his younger brother, Shiyas Abdul Rahman, 26 - grew more devout, relatives said. They stopped going to movies and deleted family photos from their mobile phones because images of people were forbidden.

At one point, Mr Hamza left an angry voice message for a nephew who had also vanished. The nephew responded with a photo of an AK-47 gun. "We are not going to come back. We are devoted to (ISIS leader) Abu Bakr al-Baghdadi. We'll meet again in paradise," the nephew texted.

WASHINGTON POST