The Islamic State group has claimed responsibility for a suicide attack in northwest Syria that killed at least 14 insurgents.

IS said in a statement on Monday the attack against Ahrar al-Sham fighters was carried out by one of its members who parked his booby trapped motorcycle outside the group’s office and detonated it along with an explosive belt he was wearing.

Ahrar al-Sham had blamed IS for Sunday’s attack in the village of Tal Touqan in Idlib province. Ahrar al-Sham said the attacker blew himself and his motorcycle up amid the fighters, killing and wounding dozens.

The opposition-operated Baladi News Network quoted a witness as saying at least 15 people were killed while the Britain-based Syrian Observatory for Human Rights said 14 were killed, including a local leader.