The so-called Islamic State (IS) released a grisly video on Saturday depicting the execution of 25 Syrian government soldiers by young militants in an ancient amphitheater in Palmyra, Syria.

IS captured the city on May 21, and the Syrian Observatory for Human Rights (SOHR), a UK-based monitoring group, reported that the executions took place on May 27.

The video, nearly 10 minutes long, was originally shared on the IS media site Isdarat. VICE News could not independently verify the authenticity of the footage, but it bears many of the hallmarks of previous IS propaganda films.

In the video, 25 bloodied Syrians are lined up kneeling, their hands bound behind their backs, on the stage of the Roman theatre at Palmyra. A large black IS banner hangs from the second-century ruins.

(Photo via al-Furqan Media/Islamic State)

A small crowd of onlookers — a few men in fatigues, but mostly in civilian clothes — are gathered on stadium seating. Young IS soldiers — including several that seem to be barely in their teens — line up one by one behind the line of kneeling men.

After a long speech, the young soldiers draw their pistols simultaneously and unleash a rapid stream of bullets at point-blank range into the backs of the soldiers' heads. The camera then pans over the line of lifeless bodies, lingering on the faces.

A large explosion is also seen in the video, which according to the SOHR is the demolition of the Assad regime's notorious Tadmur prison in Palmyra. Another soldier is also shown having his throat slit in a separate execution in front of an Assad mural at the prison.

On Friday, IS released a video showing militants using a sledgehammer to smash centuries-old artifacts from Palmyra, which is a UNESCO heritage site. According to AFP, the group has desecrated Muslim graves and destroyed a statue outside the Palmyra Museum.

A report Saturday also claimed that IS recently executed 13 top commanders after a failed plot to overthrow leader Abu Bakr al-Baghdadi. The London-based Arabic language newspaper Alaraby Aljadeed quoted Syrian and Iraqi sources in reporting on the alleged coup attempt, and said that the executed militants were from northern Africa, Syria, Yemen, and Kuwait, and included one Chechen and one Kurd.