Smoke rises from the site of a bomb attack in Erbil, the capital of Iraq’s Kurdistan region, April 17.

ERBIL — Kurdish authorities have arrested five men they say carried out a car bombing on behalf of “Islamic State” that killed two people outside the U.S. consulate in their autonomous region of northern Iraq.

Four of the men are Kurds from Erbil, the region’s Security Council said in a statement on Tuesday, highlighting the threat posed by homegrown militants in the relatively safe region. The fifth was an Arab from elsewhere in Iraq.

“The arrests were made based on information from the public and, in some cases, family members,” read the statement. “Each member of the group has confessed about their role in the attack.”

According to a video of the confessions seen by Reuters, the ringleader was a 25-year old engineering graduate named Darya Homdamin, whom the other three Kurds identified as introducing them to jihadist thought after they met through a local mosque.

The men all appeared at ease describing the details of how they carried out the attack, and showed no signs of abuse.

Darya said he had made contact via Facebook with a Kurdish militant called Mala Shwan, a cleric from Erbil who joined ISIS and has appeared in a number of the group’s propaganda videos. Mala Shwan encouraged his new protege to mount attacks inside Erbil, and put him in touch with an Arab living in Kirkuk who would eventually hand over the car bomb and show them how to detonate it.

Most Kurds are Sunni Muslim but identify more strongly with their ethnicity, and have emerged as a key partner for the U.S.-led coalition in its campaign against ISIS.