|Hurghada is one of Egypt's most popular beach resorts|
All the victims of the attack in the Red Sea resort town of Hurghada were female.
Officials said the assailant, who has been arrested, swam to the beach before attacking the tourists.
The motive for the attack is not yet known.
The tourists who died were Ukrainian, the interior ministry said.
It said the injured tourists were rushed to a local hospital but gave no further details and did not provide their nationalities.
Hurghada is one of Egypt's most popular beach resorts, particularly with Ukrainians and other European tourists.
Hurghada is a Red Sea resort town in the east of Egypt
The attack came after five police officers were shot dead in Cairo's twin city of Giza when suspected Islamic militants opened fire on their vehicle early on Friday morning.
In January 2016, three tourists in Hurghada were wounded in a stabbing attack by two assailants with apparent Islamic State group sympathies.