Forced to lie side-by-side and with their faces in the dirt, the video shows about 200 young children stretched out in a long line to the left and right.
Behind them, at least a dozen gunmen armed with assault rifles and handguns stand poised and ready to fire.
One militant then begins firing at point blank range – shooting each child individually as he makes along the row of children.
Others beside him also open fire, mostly using their machine guns, and the area is filled with dust, obscuring much of the bloodshed.
The video is believed to have been filmed somewhere inside Syria, where isis control a swathe of territory, including Raqqa, the capital of the terrorists’ self-proclaimed caliphate.
While isis is notorious for mass executions, there have been few reports of the militants targeting such a large group of children exclusively.
Although it lasts less than 30 seconds, almost all of the video is too graphic to broadcast unedited. It was not clear what the children were accused of in order to be sentenced to death.
The sound has also been redacted, though clear sustained gunfire is heard throughout the original recording.
isis is known to have executed children previously. In one instance, 1,700 Iraqi military cadets were slaughtered in a mass killing that lasted an entire day and night.
Grisly footage of the killings – likely to rank among the group’s worst atrocities – showed executions on an industrial scale.
Young men were filmed falling from trucks and pleading for their lives before being lay down in shallow graves and sprayed with bullets.