A huge blast which killed 20 people in central Cairo was caused by a speeding car packed with explosives, Egyptian officials said Monday as the president decried a "terrorist incident".
The car was driving against the traffic when it smashed into three other vehicles just before midnight Sunday evening, setting off a massive explosion just outside the country's National Cancer Institute.
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 burns of varying degrees.
Body parts were also retrieved from the scene, he added.
President Abdel Fattah al-Sisi described the blast as a "terrorist incident".
In a social media post, he offered his condolences to the victims' families and the Egyptian people.
The interior ministry said a technical inspection indicated "an amount of explosives was inside the car, which caused it to explode when it collided."
Both the ministry and 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 treatment.