Firefighters managed to contain the blaze at the facility in Ismailia, and local hospitals have been placed on alert.
Videos posted on social media show the building – which is staffed by police 24 hours a day – covered in flames.
The cause of the fire is unknown, and the government has not commented.
Civil defence sources said that the fire caused parts of the headquarters of the Directorate of Security to collapse.
Egypt’s health ministry has sent 50 ambulances and two military aircraft to the building, with at least 24 people being treated for asphyxiation along with two for burns.
There are fears that the number of people injured could be higher with one Egyptian journalist reporting that because of the size of the fire, there could be deaths.
Two witnesses who spoke to the Reuters news agency said that firefighters initially struggled to get the fire under control, but local media says that after more than three hours they did manage to contain it.
Deadly fires are not uncommon in Egypt due to fire codes rarely being enforced and slow emergency response times. In August last year, a fire caused by a short circuit killed 41 people in a church in Cairo.
Abhinav Thawait is a globe-trotting correspondent with a passion for international affairs. With a background in international relations, he offers a global perspective on the most pressing issues around the world. Abhinav’s curiosity takes his to the far corners of the earth, where he seeks to share untold stories and diverse viewpoints.