ISIS published, yesterday Saturday, through its channels on the Telegram app, what it said was a video clip of the attack on a concert hall near the Russian capital Moscow.

According to Reuters, the video clip, which lasts one minute and 31 seconds, shows a close-up shot of one of the gunmen opening fire on several people as he enters what appears to be the concert hall.

An American official told Reuters that the United States has intelligence confirming ISIS's claim of responsibility for a shooting attack that resulted in casualties targeting a concert near Moscow on Friday.

Reuters reviewed information about the Afghan branch of the organization known as ISIS Khorasan Province and the motives behind attacking Russia.

ISIS – Khorasan Province appeared in eastern Afghanistan in late 2014 and quickly became notorious for its extreme brutality, deriving the name Khorasan from an old word referring to a region that included parts of Iran, Turkmenistan, and Afghanistan.

Security analysts said yesterday Saturday that ISIS's claim of responsibility for the incident seems credible and aligns with the pattern of previous attacks carried out by gunmen.

However, a prominent expert said the surprising and unusual thing is that the attackers planned an escape and executed it instead of continuing the attack until they were eliminated.

ISIS issued statements announcing their responsibility for Friday's attack, which Russian investigators said killed 145 people.

The organization published a picture of those it said were the gunmen who carried out the attack.