The Islamic State in Iraq and Greater Syria (ISIS) has been using chemical weapons against Kurdish forces and civilians, according to an investigation in Iraq and Syria, including three known cases in the last month.

On three occasions in the last month, ISIS used chemical munitions to fight the Kurds, adapting suicide bombs and improvised explosive devices (IEDs) to include chlorine and other chemicals, CNN reported according to research by two independent U.K.-based groups, Conflict Armament Research (CAR) and Sahan Research.

One of the attacks was “the first documented use by (ISIS) forces of projectile-delivered chemical agents against Kurdish forces and civilian targets,” said CAR.

ISIS forces, for example, has fired munitions at Kurdish positions in northern Syria that had caused loss of focus, temporary paralysis, loss of consciousness and other problems, according to the investigators. At the scenes of one attack, investigators found dark yellow, powerful-smelling liquid leaking from a spent mortar, causing headaches and nausea among the team.

ISIS has been known to use chemical weapons in the past, and with access to weaponized chemical agents, its likely ISIS will continue to use the weapons, according to investigators.

[CNN]

Read next: Children Told to Behead Dolls at ISIS Training Camps

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