An explosion in Paris Wednesday sent firefighters rushing to put out a blaze that engulfed the central area of France's capital city. 

Firefighters fought the flames on Paris' Left Bank on Wednesday that sent smoke soaring over the domed Pantheon monument and prompted evacuation of buildings in the neighborhood, police said. Local media cited witnesses describing a large explosion preceding the fire, and saying that part of a building collapsed.

Florence Berthout, mayor for Paris' fifth district, said at least four people are in critical condition after an explosion occurred earlier in the day, according to Reuters. French outlet BFM TV reported that at least seven people are hurt as the fire of "unknown" origin blazes. 

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The outlet said the facade of the Paris American Academy, a bilingual fashion design school, collapsed, with debris littering rue Saint-Jacques. 

One impacted building is adjacent to the Val-de-Grâce hospital, BFM says. 

Paris police spokeswoman Loubna Atta said it was too early to determine the source of the fire and could not confirm reports it was a caused by a gas explosion, The Associated Press reported. BFM TV showed fire services sealing off the streets surrounding the fire and hosing down a building, Reuters said.

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Parisians shared photos and video to Twitter revealing a massive plume of smoke visible across much of the city.

Photos also showed armed French soldiers guarding the streets surrounding the fire. 

Journalist Olivier Galzi also told BFM TV that he witnessed the facade of a nearby building "completely collapse."

This is a developing story. Please check back for updates. The Associated Press contributed to this report.