Islamic State fighters shot down an Iraqi army helicopter over Mosul on Thursday, killing the two-member crew, the government said.
Ground fire downed the chopper somewhere in eastern Mosul, according to defense officials. Footage from an Associated Press cameraman showed a large ball of fire with a long trail of thick black smoke as the aircraft fell out of the sky Thursday afternoon.
It marked the first time ISIS shot down aircraft over Mosul since the U.S.-backed Iraqi military operation to retake the city started last October, the Jerusalem Post reported.
Iraqi air force and army aircraft conduct regular strike operations over the city to support police and special forces units battling the terrorists.
The Mosul attack came one day after ISIS fighters killed 33 young men in eastern Syria, close to the border with Iraq, according to Syrian opposition activists. The killers slit the throats of the men, aged 18 to 25, according to the Britain-based Syrian Observatory for Human Rights.
ISIS has faced a string of defeats over the past two years -- most recently in Mosul where Iraqi forces have been battling to drive the extremists out of the western part of the city, a more densely populated area. Eastern Mosul, which is separated by the Tigris river from the western part of the city, was declared liberated from ISIS in January.
Despite the severe setbacks, ISIS has managed to regularly launch attacks in some Iraqi cities. A series of large-scale bombings claimed by ISIS has also struck Baghdad.
Iraqi and U.S.-led international coalition officials have repeatedly warned that after Mosul, ISIS will likely return to its insurgent roots as it loses more territory in both Iraq and neighboring Syria.
The Associated Press contributed to this report.