Three people were injured when unidentified gunmen fired cartouche shots in Tahrir Square, a senior interior ministry source said Wednesday.
The source said a woman screamed for help after a man on a motorbike tried to steal her purse. When passers-by came to her rescue, the man drove away but then came back with 3 others and opened fire at them.
Police showed eyewitnesses photographs of suspected ex-convicts known to authorities and were able to identify the individuals responsible, the source said.
Cairo's Tahrir Square was the scene of the January revolution that toppled former President Hosni Mubarak, and of subsequent protests against the military rule and the current regime of President Mohamed Morsy.
Opposition activists are calling for protests in the square on 30 June to demand early presidential elections.
Edited translation from MENA