The blast caused a fire in the hospital which was later evacuated.
A multiple-car crash set off an explosion that ignited a fire at Egypt's main cancer hospital and caused 19 deaths, the government said.
The health ministry said 30 others were injured by the crash near Cairo's famed Tahrir Square late Sunday. The Interior Ministry said in a statement that a vehicle driving outside the National Cancer Institute collided with up to three other vehicles, causing the explosion.
The blast caused a fire in the hospital, which was evacuated. The fire was later brought under control, with television footage Monday morning showing shattered windows and doors. The health ministry did not say if hospital patients or staff were among the casualties.
Why the crash caused such a large explosion wasn't immediately clear.
"We heard an explosion and ... the bank entrance glass was shattered everywhere," said Abdel-Rahman Mohamed, a security officer at a bank at the opposite side of the hospital.
The health ministry said the injured people were taken to hospitals for treatment.
Road accidents are common in Egypt. The country's official statistics agency says 8,000 crashes last year caused more than 3,000 deaths and 12,000 injuries.