Two boys under the age of 18 were crucified by Islamic State in the streets of the Syrian city of al-Mayadin for not observing the laws of Ramadan, the Syrian Observatory for Human Rights reported on Monday.

The children, who were charged with the crime of “not fasting on Ramadan,” had placards around their necks announcing their crime was committed “with no religious justification,” The Independent reported.

Observatory founder Rami Abdul Rahman told The Independent that the boys had reportedly been caught eating, and their bodies were found “hanging on crossbars” near the Islamic State police headquarters. The boys were reportedly hung from their wrists, and their bodies were left on display until late Monday evening.

This is not the first time Islamic State has crucified people for breaking Shari’a law.

In May, Islamic State terrorists in Libya crucified three brothers of a local family after suspicions arose that they were supporting the local Libyan government, which under Islamic State law is equivalent to apostasy.

Meanwhile, Islamic State on Tuesday urged its followers to escalate attacks on Christians, Shi’ites and Sunnis fighting with the US-led coalition against the ultra-radical terrorist group.

Spokesman Abu Muhammad al-Adnani called on jihadists in an audio message to turn Ramadan, which began last week, into a time of “calamity for the infidels… Shi’ites and apostate Muslims,” urging more attacks in Iraq, Syria and Libya.

“Muslims everywhere, we congratulate you over the arrival of the holy month,” he said. “Be keen to conquer in this holy month and to become exposed to martyrdom.”

Adnani also called on Arabs in the Levant and Saudi Arabia to rise against their “tyrannical leaders.”

He said his group is undeterred by the US-led coalition.

Sunni tribes in Iraq were joining Islamic State after the Shi’ite-led Iraqi government and the United States had failed to bring them into Iraq’s political process, Adnani said.

“The Sunni people are now behind the jihadists… the enemies have been petrified by the daily pledges of allegiance by the chiefs of tribes to the mujahideen,” he said.

Ariel Cohen contributed to this report.