Cairo. At least 24 Egyptian police officers have been killed after they were attacked with rocket-propelled grenades in northern Sinai, security officials say.The officials said the Monday morning attack took place as the officers were driving through a village near the border town of Rafah in the volatile Sinai Peninsula.At least two others were injured when the unknown fighters fired on the officers’ buses as they headed towards Rafah on the border with the Palestinian Gaza Strip.The officials spoke on condition of anonymity as they were not authorised to talk to the media.Egypt shut Rafah border crossing, which is the only way most Palestinians in Gaza can leave the territory, after the deadly attack, a border official has told AFP news agency.Last week, Egypt said it would close the crossing indefinitely, but it was partially reopened on Saturday, according to the Hamas-run Interior Ministry in Gaza.Sinai has been witnessing almost daily attacks by suspected gunmen since the July 3 ouster of Islamist President Mohammed Morsi in a military coup.The attack was the deadliest in the Sinai in years, exceeding the toll from an August 2012 attack on Egyptian soldiers that killed 16.The security situation in the Sinai Peninsula, which borders both Gaza and Israel, has deteriorated since 2011, when president Hosni Mubarak was overthrown.According to AFP news agency, at least 49 security officials have been killed in Sinai since July 5 not including those in the latest attack.The army says it has killed nearly 70 "terrorists” in the region since July 3.The violence comes as Egypt wrestles with a deep political crisis and bloodshed that has left hundreds of people dead in days of clashes between anti-coup protesters and security forces.