Islamic State is claiming responsibility for a massive terrorist attack on Egyptian army checkpoints on the Sinai Peninsula Wednesday, killing at least 64 soldiers.
Egyptian military officials say security forces killed 100 militants during the day-long fighting.
One top official said the attack was "unprecedented in the number of terrorists involved and the types of weapons they are using," including rocket-propelled grenades and car bombs.
The fighting was concentrated near the town of Sheikh Zuweid. Egypt's Islamic State affiliate says 15 separate military checkpoints were targeted.
El-Sissi vows crackdown
Earlier this week, Egyptian President Abdel-Fattah el-Sissi vowed to crack down hard on Islamic militants after a roadside bomb killed the government's top prosecutor, Hisham Barakat.
The president spoke at Barakat's funeral Tuesday, pounding his fist on a lectern as he blaming the killing on the outlawed Muslim Brotherhood.
Islamic extremists have increasingly attacked Egyptian security forces on Sinai since. Sissi, who once was the military chief, led the army's overthrow of the Muslim Brotherhood's pro-Islamist President Mohamed Morsi in 2013.
The prosecutor had overseen the cases against thousands of Islamists, who have been jailed and convicted in mass trials as part of a massive crackdown since Morsi was pushed from office.
Sissi did not give details of his planned reforms, saying they would be unveiled in the coming days.