The extremist group claimed the attack in a statement late Saturday carried by its Amaq news agency.
The attack took place Friday afternoon when armed militants opened fire on police in Ismailia. At least 12 people, mostly conscripts, were wounded in the attack.
The dead included three police officers and a still unidentified person, according to a hospital tally document obtained by The Associated Press.
The state-run al-Qahera News television station reported that security forces killed one of the attackers.
Egypt has been battling IS in the northern part of the Sinai Peninsula for years. The militants have carried out numerous attacks in Sinai and elsewhere in the country mainly targeting security forces, minority Christians and those who they accuse of collaborating with the military and police.