The ISIS group said it placed a bomb in a vehicle belonging to Saber Siam and detonated it, Zionist broadcaster Arutz Sheva reported.

The Islamic State group, also known as ISIS, considers Hamas "heretical," accusing the group of conducting a war on religion.

ISIS has warned Hamas to “end its war against religion in Gaza” or “face the consequences,” Arutz Sheva said.

Residents of Gaza have been warned to stay away from government offices. Israeli sources told the broadcaster a group of Salafist rebels is trying to take over Gaza.

Earlier this month, a group calling itself Supporters of “Islamic State of Iraq and Syria” in “Jerusalem” conducted a mortar attack on Khan Yunis, targeting Izzadin Kassam, military wing of Hamas, Agence Frence-Presse reported.

The attack may have been retaliation for a Hamas attack on a mosque in Deir el-Balah favored by ISIS supporters, but which Hamas said is frequented by radicals plotting against the government.

Hamas has arrested dozens of Islamic State group supporters in recent weeks, following the ISIS takeover of the Yarmouk Palestinian refugee camp near Damascus in a massive crackdown on what Hamas describes as extremist elements.

Hamas swore to avenge the execution of a senior Hamas official inside the camp.

Haaretz other Israeli reported Hamas doesn't see the ISIS supporters as a real threat, believing they lack the logistical and financial wherewithal to oust Hamas. Nevertheless, Hamas' security services were reported on high alert.

During the mosque raid, Hamas also arrested several members of Ansar Bayt al-Maqdis, an Egyptian militant group that last year became ISIS' first branch outside of Iraq and Syria.

“In the light of Hamas’ new crackdown, we renew our loyalty to ISIS "Caliph" Abu Bakr al-Baghdadi and call on him to strengthen his influence and to launch a campaign in Palestine,” said a statement from Supporters of the ISIS released after the destruction of the mosque.