Egyptian Air Force deployed fighter jets in the Sinai Peninsula on Monday in the wake of the Kerem Shalom border attack, for the first time since the Egypt-Israel peace treaty was signed in 1979, Egyptian news agencies reported.

Two fighter jets, armed with attack missiles, arrived in El Arish early Monday morning to assist in the effort to track down the fugitive terrorists responsible for the killing of 16 Egyptian soldiers on the border with Israel, a high-ranking security official in northern Sinai told the Egyptian news site Al Masrawi. The source added that more military aircraft were on their way.

He also said that within 48 hours, large military reinforcements would arrive in Sinai — a special measure coordinated with Israel in order to help track down the terrorists in Sinai’s rough terrain.

According to the official announcement by the Supreme Council of the Egyptian Armed Forces, 35 terrorists carried out the Kerem Shalom attack, some 30 of whom were still on the run. SCAF also reported that elements from the Gaza Strip assisted in the terrorist attack by firing mortars at Israel prior to the assault.

The Sinai has seen a surge of violence since Hosni Mubarak’s ouster last year, but Sunday’s attack was the worst in several years. Suspected Islamists attacked the checkpoint in the border town of Rafah at sunset, killing the Egyptian soldiers as they were sitting down for the traditional meal breaking the fast in the holy month of Ramadan.

The attackers then commandeered two of their vehicles and burst through a security fence into Israel, according to Israeli officials. Israel said the incursion was quickly spotted and hit with an airstrike. Egypt’s military said only one armored vehicle was commandeered.

The unrest in Sinai poses a daunting challenge to President Mohammed Morsi, who since coming into office a little more than a month ago has been urged by Gaza’s Hamas rulers to warm relations with them. Hamas officials condemned the killings, vowed to help investigate it, and set up a symbolic mourning tent for the Egyptian victims.

Morsi vowed on Sunday night to make the killers pay for their crime and to restore security to Sinai, home to several of the most popular Red Sea resorts in Egypt. On Monday, he declared three days of mourning for the victims, according to state television.

“This is a huge calamity for Egypt,” declared his spokesman Yasser Ali.