EL-ARISH, Egypt -- Islamic State of Iraq and Syria (ISIS) militants ambushed a police convoy in Egypt's Sinai Peninsula on Monday, killing 18 police and wounding seven others in one of the deadliest attacks this year in the restive region bordering Israel and the Gaza Strip.

Police and military officials said roadside bombs destroyed and set ablaze four armored vehicles and a fifth carrying signal-jamming equipment meant to neutralize roadside bombs that are remotely detonated. The gunmen later opened fire with machine guns and commandeered a police pickup truck.

Among those killed were two police lieutenants. The wounded included a police brigadier general, according to the officials, speaking on condition of anonymity because they were not authorized to brief media.

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ISIS, which is spearheading an insurgency centered in northern Sinai, claimed responsibility for the attack on its Amaq news agency.

The Interior Ministry, which oversees the police, issued a statement confirming the incident, but its account provided no details on casualty figures or how many vehicles were destroyed.

It said police traveling in the convoy fired at a car that rushed toward them, causing it to blow up and damage several of the convoy's vehicles. That was followed by an exchange of gunfire with "terrorist elements" hiding in the desert on both sides of the road.

"That led to the martyrdom and wounding of some of the convoy's personnel," it cryptically added.

"Reinforcements were swiftly sent, the site has been sealed off and combing operations are underway," it said.

Egypt's Cabinet issued a statement in response to the attack, reiterating the country's resolve to stamp out terrorism and hunt down militants. Again, the statement provided no casualty figures or details of the attack.

"The United States strongly condemns the terrorist attack on a security convoy in Egypt today that left at least 18 dead and others injured," U.S. State Department spokesperson Heather Nauert said in a statement. "We express our profound condolences to the families and friends of the victims and our wishes for a speedy recovery for those hurt in the attack. We will continue to stand with Egypt as it confronts the threat from terrorism."

Monday's attack took place on a road on the western fringes of the coastal city of el-Arish in northern Sinai, a rugged region defined by desert, shrubs and mountains. It showed the resilience of the militants in the face of a years-long campaign to eradicate them by the military and police, which between them command far superior firepower, air support, heavy armor and larger numbers.

The attack also suggested that the militants remain capable of carefully planning elaborate and multi-tiered attacks, making full use of the weapons available to them and their knowledge of the local terrain. In a wider context, the militants have been seeking to demoralize troops using snipers, killing at least 14 policemen and soldiers in recent weeks.

They have also been increasingly using brutal methods to discourage civilians from cooperating with the security forces, kidnapping alleged collaborators and later dumping their decapitated bodies on the streets to terrorize the population.

Egypt's security forces, meanwhile, have succeeded in confining the insurgency to northern Sinai -- a remote northeastern corner of the country -- and preventing the militants from seizing and holding territory there.

Monday's attack was the deadliest against security forces since July, when ISIS militants attacked a remote army outpost in the border town of Rafah, killing 23 soldiers. That was the deadliest attack in two years.

In March, the military said militants killed 10 soldiers during an army raid in Sinai's central region.

Egypt has battled militants in Sinai for years, but the insurgency became far more deadly after the 2013 military ouster of Mohammed Morsi, an elected Islamist president. It has since waged a number of high-profile attacks on the mainland, including areas near Egypt's porous desert border with Libya. Egypt maintains that some of the militants attacking its security forces and minority Christians sneak into the country through the Libyan border carrying weapons.

In recent years there has also been a wave of attacks, mainly targeting security forces, blamed on splinter factions of Morsi's Muslim Brotherhood group.

Monday's attack came a day after authorities said they had busted a militant cell planning attacks in Cairo. Police said they killed 10 militants in two simultaneous raids on apartments in a densely populated Cairo neighborhood. They said the militants sneaked into the capital from northern Sinai, but did not say whether they were members of the ISIS group.