GAZA — The local leader of an extremist Islamic splinter group was fatally shot Tuesday in a clash with Hamas forces who had come to arrest him. The death raised tensions in Gaza at a time when Hamas, which controls the territory, has been cracking down on radical jihadists.

Iyad al-Buzom, a spokesman for the Interior Ministry in the territory, said the man had been shot after he refused to surrender and opened fire on security forces. Writing on his Facebook page, Mr. Buzom added that the man, whom he called an outlaw, had booby-trapped his house, and that Hamas forces had found explosive belts, bombs, rocket-propelled grenades and various other weapons there.

But a brother of the dead man said he had been killed because he “rebelled against Hamas” and because he supported the Islamic State and the imposition of Islamic law.

The dead man was identified by relatives as Younis Hounor, 27. According to Muhammad Hounor, his brother, he spent four years as a fighter in the military wing of Hamas before joining the more radical Salafist stream of Islam about two years ago.