The early morning blast on January 12, 2019, destroyed a building housing a bakery and restaurant on the Rue de Trevise in the Ninth Arrondissement and severely damaged several adjacent buildings.
The shockwave overturned cars and shattered windows as far as two blocks away, leaving scenes of devastation reminiscent of a combat zone. The street in front still remains off limits except for residents.
The four victims included a Spanish woman on vacation with her husband and dozens of families living nearby were forced to evacuate their homes for months.
While the cause of the blast was not immediately known, an expert report released earlier this year suggested that a caved-in pavement in front of the building had caused a leak in a buried gas pipe.
Several residents said they had petitioned city officials for years to repair the collapsed sidewalk, while also urging the building's property management firm to repair a sewer main in the basement.
The report determined that the leaking sewer line may have caused the pavement to collapse and judicial sources said the property firm was also charged with involuntary manslaughter last week.
The construction company tasked with repairing the pavement has been made an official witness in the case.
A lawyer for the city, Sabrina Goldman, rejected the report's findings, telling AFP that "we believe that we did nothing wrong with regards to this accident".
But Olivier Morice, a lawyer representing 17 civil plaintiffs, said the charges were the logical outcome of the expert report and urged city officials to "face their responsibilities".