GAZA — A series of explosions destroyed several vehicles belonging to officials of the militant Islamist groups Hamas and Islamic Jihad on Sunday, the latest in a series of attacks in Gaza attributed to extremists who have aligned themselves with the Islamic State.

Witnesses told local journalists that there were four explosions at three sites in the Sheikh Radwan neighborhood of the Palestinian coastal enclave of Gaza around 6 a.m. At one location there was new graffiti of the Islamic State flag with the declaration “Shariah will win,” referring to the legal code of Islam based on the Quran.

Health officials in Gaza said two people in nearby homes were injured by shattered glass. Photographs posted to social media showed a dark gray truck with its back blown off and the shell of a badly burned sedan.

“Some sinful hands are trying to undermine the resistance,” the military wings of Hamas and Islamic Jihad said in a joint statement. “The perpetrators put themselves in the box of treason,” the groups added, saying such attacks serve Israel’s “objectives” in destabilizing Gaza.