Khaled Desouki, AFP| Egyptians walk outside the National Cancer Institute in Cairo on August 5, where a blast just before midnight the previous day killed at least 19 people and wounded more than 30.

A huge explosion caused by a speeding car in central Cairo overnight, killing at least 20 people, was a "terrorist incident," Egypt's president said Monday.

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"I extend my deepest condolences to the Egyptian people and the families of the martyrs killed in the cowardly terrorist incident," read a post on Abdel Fattah al-Sisi's official Facebook and Twitter feeds.

The collision happened just before midnight Sunday, when a speeding car driving against the traffic crashed into three other vehicles outside the National Cancer Institute in the Egyptian capital.

Four of the 20 people killed remain unidentified, the health ministry said, while 47 others were wounded.

Between "three and four (of the injured) are in critical condition in the intensive care unit," Khaled Megahed, a spokesman for the health ministry, told a press conference.

He said they suffered from "several burns of varying degrees".

Body parts were also retrieved from the scene, he added.

Egypt's prosecutor general has ordered an investigation to determine the causes of the collision.

Police said they suspected the Hasm group, an armed affiliate of the Muslim Brotherhood, of being behind the attack.

Social media users posted footage of cars ablaze at the scene and of patients being evacuated from the Cancer Institute, which was severely damaged and charred in the explosion.

Megahed said 78 cancer patients from the institute were moved to other hospitals to continue their treatments.

(AFP)

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