Horrifying images showing the crucifixion and execution of four men in the middle of a Raqqa street as the ISIS (So-called Islamic State , ISIL, Daesh) terror group suffers heavy losses toward Syrian troops.

The executions took place in Raqqa April 2, according to the activist group Raqqa is Being Slaughtered Silently.

The killings were held as ISIS suffered heavy losses in the north of the city, with the largely Kurdish Syrian Democratic Forces backed by US-led air strikes gaining significant ground, Daily Mail reports.

Last week, it was claimed ISIS killed 15 of its own members in the largest ISIS execution memebers  of the militant group's security services so far in Syria.

The killings follow the arrest of 35 members in Raqqa at the weekend, according to the Syrian Observatory for Human Rights, which monitors the Syrian conflict through a network of sources on the ground after terror group lose ancient city of Palmyra then push back terrorist from city of Qaryatain.

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