Mosul-Terror group ISIS shot down an Iraqi helicopter operating over Mosul Thursday, as security forces announced they recaptured another neighborhood in their nearly six-month-old offensive against the terrorists’ stronghold.

The operation to retake west Mosul — which the helicopter was supporting when it was downed — has become a slow, grinding battle that has taken a heavy toll on civilians and pushed more than 200,000 to flee.

“The helicopter was supporting federal police forces in (west Mosul) and was hit by fire and crashed in the Mohandiseen neighborhood in east Mosul,” Brigadier General Yahya Rasool, the spokesman for Iraq’s Joint Operations Command, told AFP.

The city is divided by the Tigris River. East Mosul was recaptured earlier this year, but ISIS still holds significant ground on the city’s western side.

Federal police are operating alongside interior ministry special forces in Mosul’s Old City — a densely populated warren of narrow streets and closely spaced buildings that is home to hundreds of thousands of people.

Rasool said the US-made Bell helicopter crashed on Thursday, and that he believed it was hit by 57 mm anti-aircraft fire.

Iraqi army aviation operates armed versions of the Bell 407 helicopter.

Strikes by Iraqi helicopters are especially important for the country’s interior ministry forces, which have consistently complained of not receiving sufficient air support from the US-led anti-ISIS coalition during the Mosul operation.

The downing of the aircraft on Thursday comes after another helicopter crashed south of Mosul at the beginning of the year due to a “technical failure,” killing four crew members.