The discovery of the sarcophagus on a construction site in June is a rare find in Alexandria, a fabled port city where most traces of Egypt's ancient civilizations have crumbled into the waves or lie buried beneath urban sprawl.
The ancient coffin is the largest to be discovered in Alexandria.
Waziri stressed that none of the three mummies belong to a Ptolemaic or Roman royal family and the coffin does not have inscriptions or a cartouche bearing their names.
The ancient sealed sarcophagus was opened to reveal the remains of three people, covered in a red-brown liquid understood to be sewage water that leaked into the casket through a crack.
This was one of several indications that had some people suspecting that the sarcophagus could contain the long-lost remains of Alexander the Great, who founded Alexandria. "Unfortunately, the mummies inside were not in the best condition and only the bones remain", Mostafa Waziri, secretary-general of the Supreme Council of Antiquities, said.
Some observers thought it might contain the corpse of Alexander the Great, as the sarcophagus dates back to the early Ptolemaic period (about 323 BC), which began after his death.
Egyptian researchers opened a mysterious, 2,000-year-old sarcophagus Thursday, ending a two-week long mystery about what existed inside, according to BBC News.
The box itself weight 27 tonnes, and is nearly three metres long, the largest structure of its kind ever found intact.
A handout photo made available by the Egyptian Ministry of Antiquities shows workers removing sewer water submerging three decomposed mummies after opening the black granite sarcophagus that was discovered in Sidi Gaber district, Alexandria, Egypt, 19 July 2018.
There was also a lot of online chatter about the possibility of unleashing a curse by opening the presumed 2,000-year-old coffin.
"The sarcophagus has been opened, but we have not been hit by a curse", Waziri said.
The skull of one is said to show cracks which point to an arrow injury. The skeletons will be taken to the Alexandria's National Restoration Museum for further analysis to determine their cause of death.