Fighters from the Islamic State in Iraq and Greater Syria (ISIS) set fire to the Ajil oil wells in east of the city of Tikrit in hopes of stopping aerial attacks that would drive them out of the oilfield, witnesses tell Reuters.

The oil field used to produce about 25,000 barrels per day of crude oil before ISIS took it over in June.

Shi’ite militia and Iraqi soldiers began moving through Ajil Monday in an assault on ISIS-held Tikrit. Security sources told BBC that the forces surrounding the city from the east, south and north have captured villages and oil fields east of the city, but that ISIS was fighting back with suicide bombers and snipers.

[Reuters]

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Write to Eliana Dockterman at eliana.dockterman@time.com.