French rescuers scoured the rubble for a missing person on Thursday, a day after a blast ripped through a building in central Paris, leaving four seriously injured.

On Wednesday afternoon an explosion tore through a building on Saint-Jacques Street in the 5th district, close to the Luxembourg Gardens and at the edge of the Latin Quarter, a top tourism area in the French capital.

The blast left four people seriously injured, while 33 others sustained lesser injuries, according to police.

"The search is continuing," police told AFP on Thursday, saying rescuers were looking for one person still not accounted for -- down from two earlier Thursday morning.

The blast blew out windows up to 400 metres (yards) away, and was followed by a major fire which caused the building, housing a fashion school, to collapse.

Some 70 fire trucks and 270 firefighters battled the blaze before it was contained.

Early Thursday, the security cordon had been reduced, allowing journalists and gawkers closer to the heap of rubble in front of the structure.

A single fire hose was still spraying the remains of the building now and then, while some shops had reopened on the street of the blast.

The mayor of the 5th district said a gas explosion was behind the collapse, but this has not yet been confirmed by other officials.

Some witnesses spoken to by AFP reported noticing a strong smell of gas in the street before the explosion, but officials said they did not have enough evidence to determine the cause of the blast with certainty.

An investigation into the causes was launched immediately, prosecutors said.

There have been several incidents of gas-related blasts in the French capital.

In January 2019, a suspected leak in a buried gas pipe destroyed a building on the Rue de Trevise in the ninth district, killing four people including two firefighters.

The shockwave blew out scores of nearby windows, and dozens of families were forced to evacuate their homes for months. 

Much of the street still remains off limits four years after the disaster.  

sm-mk-al-pa/bfa/yad-tgb