Baghdad, AP—Iraqi soldiers backed by Sunni fighters launched a major operation Saturday to retake a section of the city of Ramadi seized by Islamic State of Iraq and Syria (ISIS) militants, an official and residents said.

The fighting focused on Ramadi’s eastern Sijariya neighborhood, which the extremist group said it captured on Friday. An official with the Anbar provincial council described intense fighting there Saturday morning that included both sides firing mortars. He spoke on condition of anonymity because he was not authorized to brief journalists.

Eyewitnesses there, speaking on condition of anonymity for fear of reprisals, corroborated his account.

ISIS has been trying to seize Ramadi, the capital of Anbar province, for months now. Sunni militants including the group’s fighters seized parts of it last January.

The Anbar official also said ISIS fighters lined up and shot several men Friday from the Boufahd tribe, which is taking part in the fight against the militant group.

ISIS fighters have killed more than 200 men, women and children from Anbar’s Sunni Albunimr tribe in recent weeks, apparently in revenge for the tribe’s siding with Iraqi security forces and, in the past, with US forces.

Earlier this month, an American advisory mission visited Anbar’s Al-Asad air base, searching for potential training locations for fighters battling ISIS, which holds a third of both Iraq and Syria in its self-proclaimed caliphate. The move is part of a US plan to train Iraqi forces and Sunni tribesmen, reminiscent of the Sunni Awakening movement that confronted Al-Qaeda in Iraq starting in 2006.