Nineteen people died and 30 were injured in an explosion resulting from a car crash in central Cairo, Egypt's health ministry said on Monday.
There was no official statement indicating that the explosion was an attack.
The blast happened when a car driving against traffic on Cairo's Nile corniche road collided with three other cars, the interior ministry said in a separate statement.
It triggered a blaze that forced the partial evacuation of a nearby hospital, National Cancer Institute, the health ministry said.
Shortly after the explosion, blazing cars could be seen in the roadway as passers-by struggled to help the injured.
Later in the morning, investigators scoured the scene amid a heavy police presence. The hospital building showed apparent damage up to the third floor, a Reuters witness said.
Egypt's public prosecutor is investigating the incident, sources told Reuters.