(Bloomberg) --

A gas explosion on Paris’s left bank late Wednesday afternoon left around 50 people wounded and destroyed the facade of a building.

Six of the victims are in critical condition and one person is still missing, the Paris prosecutor’s office said on Thursday.

The explosion occurred in a building that housed the Paris American Academy, a bilingual design school, local media reported. The blast, near the Val de Grace church, prompted fires in nearby buildings.

Edouard Civel, an official from the 5th arrondissement, where the explosion happened, asked residents in a tweet to stay away to allow firefighters to operate.

Mayor Anne Hidalgo arrived at the scene shortly after the incident.

(Updates with number of injured and missing from first paragraph.)