The United States on Thursday condemned an earlier bomb attack in an open-air market in Cairo's Old City, a US Embassy source told Xinhua.

The attack, which took place at around 5:00 p.m. (1500 GMT) in the market close to al-Azhar mosque, one of the most revered shrines in the Sunni Muslim world, killed innocent people, the source said.

The United State hoped that the Egyptian authorities could make a quick investigation and punish the perpetrator as soon as possible, the source said.

The powerful blast killed four people, including a French woman, and wounded 18 others of various nationalities, Egyptian hospital sources said.

Source: Xinhua