An explosive-laden drone, sent by the Islamic State group (ISIS), was intercepted and shot by Kurdish forces in Iraq early this month, according to reports Tuesday. However, the drone blew up and killed two Kurdish fighters and injured two French soldiers.

The incident reportedly happened on Oct. 2 in Erbil, which serves as the capital of Iraqi Kurdistan, where French troops have been fighting along with Kurdish fighters against ISIS, according to the New York Times and French newspaper Le Monde. Neither Iraqi officials nor French authorities have confirmed the incident.

About 500 French military personnel have been deployed in Iraq to fight ISIS. They include special forces who are training Kurdish Peshmerga forces in the northern part of the country. The French defense ministry declined to comment on the latest incident, according to Le Monde.

However, American authorities told the Times that the militants masked a battery in the drone as an explosive device.

“The explosive device inside was disguised as a battery — there was a very small amount of explosives in it, but it was enough to go off and kill them,” a senior U.S. official told the Times.

Three reported drone attacks in Iraq have been attributed to ISIS. However, the latest incident was the one that reportedly caused casualties marking the terror group’s first successful attempt to attack Western forces by drones.

The use of unmanned aerial vehicles by ISIS has concerned American authorities. The militant group is reported to be using commercially available drones that can be bought from Amazon, unlike the U.S. military that operates drones the size of a small passenger plane.

The Central Intelligence Agency and the Defense Intelligence Agency are examining the use of drones by ISIS, according to the Times. Eric Fanning, the secretary of the U.S. Army, recently assigned a newly created special office to respond to growing threats and to study how to avert enemy drones, the report added.