Gunmen attack police station in Egypt's Sinai

Meanwhile, the military sent additional armored and other army vehicles to boost its strength in a hunt for militants in the wake of a deadly weekend attack that killed 16 Egyptian soldiers.

The security officials also said army engineers were making preparations to destroy or shut an elaborate underground tunnel network linking Sinai and Gaza that is used to smuggle weapons, people and basic goods to circumvent border restrictions imposed against the Hamas-controlled territory by Israel and Egypt. The officials all spoke on condition of anonymity because they were not authorized to discuss ongoing operations.

The lawlessness in northern Sinai, which borders both Gaza and Israel, reached a new level with Sunday's attack on an Egyptian military border post. The attackers killed the 16 soldiers as they were breaking their daily fast for the holy month of Ramadan with a sunset meal. They then commandeered an armored vehicle, which they later used to storm across the border into Israel where they were hit by an Israeli airstrike that killed at least six militants.

The attack has rattled the Egyptian government, prompting the country's new Islamist president to sack the intelligence chief for failing to act on an Israeli warning of an imminent attack just days before.

President Mohammed Morsi also sacked the northern Sinai governor. The decisions were Morsi's first moves to assert his authority amid a power struggle with the country's military leaders. But the decisions appeared to have come with the generals' approval as the nation was outraged by the militants' attack, the worst assault on troops from within Egypt in living memory.

The military also announced an offensive in Sinai designed to weed out the militants who have used the security vacuum in the desert region to spread their influence. In a sharp escalation, Egyptian warplanes struck against suspected militant hideouts on Wednesday, but there were no official reports of deaths or arrests in the operation.