Officials say Egypt has deployed at least two helicopter gunships to the Sinai Peninsula in the hunt for militants behind the killing of 16 Egyptian soldiers at a checkpoint along the border with Israel.
Security and military officials said on Monday that more aircraft were expected to arrive in the town of El-Arish ahead of a military campaign against the militants in the area. The officials spoke on condition of anonymity because they were not authorised to speak to the media.
Suspected Islamists on Sunday evening attacked the Egyptian checkpoint, killed the troops, then stole two of their vehicles and burst through a security fence into Israel. Israeli aircraft then halted their assault.
At least five gunmen were killed after they tried to infiltrate into Israel from Egypt, the Israeli military said on Monday, shortly after killing 16 Egyptian security forces in an attack on a Sinai checkpoint.
Another seven Egyptians were wounded in the initial attack, when the militants opened fire on the checkpoint and commandeered vehicles during a Ramadan fast in Rafah.
Having hijacked the vehicles, they raced to the nearby Kerem Shalom/Karm Abu Salem crossing point on the Egypt-Israel-Gaza border.
According to the Israeli military account, one of the gunmen was killed when an explosive-laden truck he was driving exploded at the Kerem Shalom checkpoint, and at least four were killed when the armoured vehicle they were in, which entered Israel, was hit in an Israeli air strike. That death toll of five could rise further, the military said.
Israelis living in the vicinity were initially ordered to remain at home behind locked doors while troops scoured the area to check if more militants were still at large.
The Israeli military ruled out earlier reports that an Israeli soldier was missing or had been abducted.
Egyptian President Mohammed Morsi promised to bring to justice the perpetrators of the attack. He promised a harsh response to the incident and said the military would bring the Sinai Peninsula under control.
Security authorities were working to determine the identities of the attackers, a spokesman for the president’s office told state-run television. No group had taken responsibility for the attacks.
Egyptian authorities closed the border crossing with the Gaza Strip at Rafah indefinitely, several news reports said.
Israeli Prime Minister Benjamin Netanyahu said Sunday night the Israel Defence Force and the Shin Bet internal security service had thwarted a major attack against Israeli citizens.
In Gaza, Hamas, which administers the enclave, denied that any of its militants had been involved in the attack on the Egyptian army post, or the attempted infiltration into Israel.
Over the past year, Islamist militants in Sinai are believed to have been responsible for several attacks on a gas pipeline that exports gas to Israel as well as attacks on police stations.
Egypt has been trying to secure the Sinai Peninsula over the past year as turmoil and soaring crime rates nationwide followed the ouster of president Hosny Mubarak in a popular revolt in February 2011.