Twenty people were killed and 47 injured when a car packed with explosives intended for a militant attack blew up outside a Cairo cancer hospital, the interior ministry said.
Officials initially said the explosion was caused when a car driving against traffic collided with three others.
The front of the hospital suffered extensive damage, with an entrance wrecked. Victims’ belongings were scattered among the debris.
The interior ministry said the car involved was stolen a few months ago.
“Initial technical examination showed the car contained explosives and the collision led to the detonation,” a ministry statement said.
“It is estimated the car was being transported for use in the execution of a terrorist operation,” the ministry added.
It said the Hasm militant group was responsible for rigging the car.
Egypt accuses Hasm, which emerged in 2016 and claimed several attacks, of being a wing of the outlawed Muslim Brotherhood. Egypt’s oldest Islamist movement denies and says it seeks change through peaceful means.
The explosion caused a blaze forcing partial evacuation of the National Cancer Institute, the health ministry said.
A resident, who gave her name as Salwa, said bodies were fused by the explosion.
“There was an extremely loud blast. It was no way two cars crashing. The car must have been rigged with explosives,” she told Reuters Television.
Another witness, who declined to give his name, said the driver ran away before it exploded.
Later investigators scoured the scene amid a heavy police presence.
Egypt’s public prosecutor is investigating the incident, sources told Reuters.
President Abdel Fattah al-Sisi expressed condolences to the Egyptian people and victims’ families. He pledged to eradicate “this brutal terrorism”.
Egyptian security forces are waging a counter-insurgency campaign against Islamist militants, some with links to Islamic State, focused on the north of the Sinai Peninsula.
Attacks outside Sinai are relatively rare, although there have been security incidents in recent months in Giza.
In May, an explosion targeting a tourist bus injured at least 12 people, mostly South African tourists, near the Giza pyramids.
In December, three Vietnamese tourists and an Egyptian guide were killed and at least 10 others injured when a roadside bomb hit their tour bus near the pyramids.