Egypt's South Cairo prosecution office has completed its initial inspection of the site of an explosion caused by a car crash in front of the National Cancer Institute in Central Cairo.

The prosecution has ordered the questioning of eyewitnesses and the collection of footage from surveillance cameras in the vicinity of the blast in Manyal neighbourhood.

The accident, which took place shortly after midnight on Monday, killed at least 20 people and injured dozens.

The prosecution has ordered the collection of footage from surveillance cameras at the NCI's entrance, as well as from the nearby National Women's Health Centre.  

At least 20 people were killed and 47 were injured, including some in critical condition, in a blast caused by a car collision in front of the NCI in central Cairo's Manyal neighborhood, according to a latest statement by Egypt's Health Ministry.

The interior ministry said hours after the blast that the explosion occurred after a speeding car moving against traffic collided with three other cars.

Cairo's 57357 Children's Cancer Hospital has released a statement mourning the death of two of its employees in the security department in the deadly collision. 

Thirty patients at the NCI have been transferred to other hospitals due to the damage caused by the blast.