Paris, June 04: Twenty-five people were injured, four seriously, in an explosion on the top floor of a building in the Sentier Garment district of central Paris today, police said. Firefighters said the blast, which took place around 11:55 am (1525 IST) in the Rue Uzes, was probably caused by a gas leak.

Some 300 firefighters, police and emergency workers were at the scene, and firefighters used sniffer dogs to look for possible casualties inside the building in the second district of the French capital.

Emergency services official Pierre Carly said the four seriously wounded had been rushed away for treatment but their lives were not threatened.

They are suffering from "classic lesions due to a blast phenomenon and projectiles (consistent with) a gas explosion in a confined space such as an apartment."

The blast destroyed much of the fourth and fifth floor of the building, as well as damaging the remaining floors and blowing out windows in the immediate vicinity.

Police said the explosion caused the building's elevator cage to collapse, while eyewitnesses said the roof had been blown off.

"What we have learned from our first inquiries is that people in the area noticed a strong smell of gas before the explosion," said Paris state prosecutor Yves Bot who visited the scene.

Paris police chief Jean-Paul Proust said the cause was "very probably accidental."

Bureau Report