A Frenchman injured in Thursday's blast at a Cairo street market died as he arrived in France for treatment, bring the death toll in the attack to four, police and the French Embassy said Sunday.
The blast also killed an American man, a French woman and an unidentified third person whom police suspect was the bomber.
A French diplomat said the Frenchman was being flown home for medical treatment but died on arrival.
According to The AP, Egyptian police disclosed Sunday that 15 people have been detained for questioning about the blast, which was caused by a seven-pound, nail-packed homemade bomb.
Authorities are investigating whether a suicide bomber carried out the bombing. Prosecutor-General Maher Abdel Wahed has said the investigation revealed that the attack was "an individual act."
Egyptian Cabinet spokesman Magdy Rady has said the bomb either exploded prematurely or the bomber intended to commit suicide in the blast.