Islamic State group militants armed with a rocket launcher shot down an Iraqi military attack helicopter Friday, killing two pilots and raising new worries about their ability to attack aircraft amid ongoing U.S.-led airstrikes.

The Mi-35 helicopter crashed outside the town of Beiji, 200 kilometers (130 miles) north of Baghdad and home to Iraq’s largest oil refinery, authorities said. Iraqi Defense Ministry spokesman Mohammed al-Askari told state-run Iraqiyya TV that the crash killed the helicopter’s two pilots and that authorities had begun an investigation.

An official with the Defense Ministry told The Associated Press the militants downed the between the towns of Beiji and al-Senniyah. An official with the Iraqi air force corroborated the information, saying the helicopter’s pilot and co-pilot were killed in the crash. […]