A would-be bomber tried to hurl an explosive device into the US Embassy in Cairo but was stopped and arrested by police, it was reported.
Security sources told Reuters that the man was detained after throwing an explosive device which detonated near the embassy.
A security source told the BBC that the man was carrying "a bag of explosives".
There were reports that the man may have been armed with a gun.
The embassy - located near to the UK's diplomatic mission - was put on lockdown and it warned American citizens to stay away from the area.