More than 20 others were injured by the blaze in El Obour, an industrial city some 35 kilometres northeast of the Egyptian capital.
An investigation is underway but reports suggest a gas cylinder exploded and that the plant did not have the safety clearances required to operate.
The factory owner and a number of other officials are said to have been detained in connection with the blaze.
Such incidents are relatively frequent in Egypt because of dilapidated buildings and safety standards being flouted.
A separate fire at a food market in Egypt’s second city of Alexandria left 11 people injured on Tuesday, a health ministry official in the city said.
At least 35 people died last week in a boat collision on the Nile that prompted criticism of Egypt’s transportation and infrastructure safety standards.
