A Syrian military aircraft crashed in the northeastern Syrian city of Raqqa, which is under the control of the Islamic State, formerly known as ISIS, Associated Press, or AP, reported citing the U.K.-based Syrian Observatory for Human Rights. 

Another Raqqa-based activist, who uses the name Fourat Alwfaa, said that the crash happened after Islamic State fighters fired several anti-aircraft weapons aimed at the aircraft, but could not confirm if these had caused the plane to crash, AP reported. However, a Reuters report, citing a local official of the human rights organization, said Islamic State fighters had shot down the plane in the first such aerial offensive by the group since it declared an Islamic caliphate in the region.

The crash killed at least eight people and reportedly prompted many to flee the region, fearing U.S. airstrikes against Islamic State militants. Last week, U.S. President Barack Obama ordered airstrikes against the Islamic State in Syria.

"By God, yes, people began fleeing about a week ago," a resident in a village close to Islamic State strongholds in the region, told AP.

The Islamic State, a Sunni extremist group that espouses an extreme version of Islam, has taken over vast swathes of northern Syria and northwestern Iraq in an attempt to establish a caliphate in the region.

Airstrikes launched by the U.S. to help beat back the group's advance have prompted the group to execute two American journalists, and David Haines, a British aid worker, in the last few weeks. On Monday, the Islamic State threatened to behead Alan Henning, another British hostage, who left his job as a cab driver in England to deliver supplies to refugees fleeing the Syrian civil war.