A US citizen has died from wounds sustained in Thursday's bomb blast in Cairo, the US in Egypt announced.
The blast occurred in old Cairo in an area popular with tourists
A French woman and another person were killed in the blast from a bomb attack in the historic heart of Cairo.
French, American and Italian tourists were among 18 people wounded when the bomb was thrown into a crowded market in the Egyptian capital.
The attack, in a part of Cairo popular with tourists, is the first in the city for seven years.
There is no indication yet of who might have been behind the bombing. US embassy official Micaela Schweitzer-Bluhm said several US citizens were among those injured in the attack, in a packed bazaar area in Cairo's old city.
Brig Gen Nabil al-Azabi, head of security in Cairo, said initial investigations suggested the explosive was a homemade nail-packed bomb that went off prematurely.
He said the unidentified corpse may be that of the man carrying the bomb.
Egypt's interior ministry said nine Egyptians and nine foreigners were hurt. Doctors said many of the wounded had severe wounds from nails packed in the bomb.
The attack happened at about 1700 (1500 GMT) on Thursday, close to al-Azhar mosque, which is a major seat of Islamic learning.
There is no indication yet of who might be have been behind the attack
The blast went off on al-Moski Street, a narrow street of tourist shops and clothes sellers - often crammed with foreigners and Egyptian shoppers, carts and peddlers - near the main bazaar of Khan al-Khalili.
Rabab Rifaat, a woman shopping nearby, told the Associated Press news agency she heard a loud "boom", and saw a severed head flying through the air.
Cairo's police chief denied earlier reports that the attacker had thrown the bomb from a motorbike, instead saying it had been tossed by a male pedestrian.
The US embassy in Cairo issued a statement warning Americans to stay away from the area of the attack.
The attack comes at a time when tourism is bringing in record revenues, says the BBC's Heba Saleh in Cairo.
Many Egyptians will now be worried about its impact on the industry, she adds.
Islamic militants in Egypt have staged attacks on tourist attractions in the past.
In the most recent attack in October 34 people died, including 12 Israelis, when militants bombed two hotels in the Sinai peninsula.
The government accused a group of Sinai residents, some of whom were killed in the attacks. Very little information has come out about them, though their leader was said to have had Islamist leanings.
In 1997 the country's lucrative tourism industry was thrown into crisis when gunmen opened fire on foreigners in central Cairo and at a site near the southern Egyptian city of Luxor. A total of 68 people died in the two attacks.
Correspondents say Egypt may be entering a period of political change.
President Hosni Mubarak, who has been the country's leader since 1981, is under growing internal and external pressure to introduce political reforms.
In February, Mr Mubarak asked parliament to change the constitution to allow multiple candidates in presidential polls for the first time.
A political movement has emerged, partly centred on the al-Ghad (Tomorrow) party, with the slogan of Kifayah (enough).
Thousands of Egyptian university students, mostly supporters of the banned Islamic Brotherhood, demonstrated earlier this week against the government, in the largest such protest yet to be staged.