TEL AVIV — Three of those responsible for the deadly Islamic State attack on Friday in northern Sinai were former members of Hamas’ so-called military wing, the Izz ad-Din al-Qassam Brigades, a senior jihadist in the Gaza Strip told Breitbart Jerusalem.

Confirming the information, on Sunday the IDF’s Coordinator of Government Activities in the Territories (COGAT) Maj. Gen. Yoav Mordechai announced that there is information four former Hamas members who joined IS took part in the attack.

On Friday, the armed jihadists attacked an Egyptian army post next to the city of Rafah. In the opening stages of the attack, the terrorists exploded two car bombs and immediately afterward opened fire on Egyptian soldiers. Twenty-three soldiers were killed in the attack and many others were wounded. All of the assailants were reportedly killed.

The Islamic State group claimed responsibility for the attack.

Among the armed militants who participated in the attack, the senior jihadist told Breitbart Jerusalem, were three former Hamas members who managed to flee the Gaza Strip recently and joined Wilyat Sinai, the Egyptian branch of IS.

According to the jihadist source in Gaza, the three were residents of the Gazan side of the city of Rafah and former members of Hamas’ “military wing.” They joined IS in Sinai some two months ago after successfully infiltrating the peninsula through the tunnels that connect the Gaza Strip to Sinai. The jihadist source said that Friday’s attack is not the first against Egyptian soldiers in which the three participated.

Hamas, seemingly with the intention of preempting an angry Egyptian reaction over the attack, quickly issued a harsh condemnation with spokesman Fawzi Barhoum calling it a crime.

“This is a cowardly terrorist act that seeks not only to undermine the security and stability of the Egyptian public, but also the stability and security of the entire Arab people and then bring the region into a whirlwind of violence. Killing and terror are part of the plot to divide the region and steal its resources,” Barhoum said in a statement.

Hamas didn’t stop with the harsh condemnation, however, and even opened a special mourning tent in honor of the Egyptian soldiers. Hamas officials were seen in the tent wearing scarfs bearing the Palestinian and Egyptian flags.

Breitbart Jerusalem recently reported on the flow of Gazans into IS’s ranks in the neighboring Sinai Peninsula.