Three people have been killed in a car-bomb blast in Giza, on the outskirts of Cairo, according to Egyptian state media.
Security officials were quoted as saying those killed were carrying an explosive device in their car and likely detonated it by mistake.
MENA news agency said the explosion took place early on Wednesday in the town of el-Saf in Giza province.
Another state news outlet, Al-Ahram, quoted Brigadier Mahmoud Shawki, a police officer, as saying those killed were likely to have been on their way to carry out a "terrorist operation".
Shawki said the car was torn into two by the blast and that security forces were trying to identify the dead, Al-Ahram reported.
Egypt has seen a wave of protests and violence since the army toppled Islamist President Mohamed Morsi last year amid mass protests against his rule.
An al-Qaeda-inspired group called Ansar Beit al-Maqdis has claimed responsibility for a series of explosions and suicide attacks over the past year.