El Arish - Islamic State 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 one carrying signal jamming equipment. 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. The officials spoke on condition of anonymity because they were not authorised to brief media.ISIS claimed responsibility for the attack in a brief item carried by its Aamaq news agency.The attack took place about 30km west of el-Arish in northern Sinai, the epicenter of a long-running insurgency now led by an ISIS affiliate.Monday's attack was the deadliest against security forces since July, when Islamic State 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. 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.