A Coptic Christian priest was killed early Thursday in North Sinai, Egypt's interior ministry announced.

Reverand Rafael Moussa, the priest of St George Church in Al-Arish, was shot down by a group of unknown assailants, the ministry said in a statement issued Thursday afternoon.

Moussa was fixing his car when he was shot, the statement added.

The murder is being investigated by authorities.

The Islamic State group's Egyptian affiliate claimed responsibility for the murder in a statement posted online, accusing the priest of "fighting Islam."

The Egyptian Orthodox Church mourned the slain priest and condemned his murder.

In July 2013, following the ouster of president Mohamed Morsi, gunmen killed another Coptic Christian priest in Al-Arish.

Egypt's security forces are fighting a decade-long Islamist insurgency in parts of North Sinai, which has spiked since 2013.

Christian citizens in North Sinai have been a target for militants, especially in Al-Arish.