Published: 2019-01-12 16:24:07 BdST
Authorities were on high alert in the French capital for a ninth consecutive Saturday of "yellow vest" protests, with large parts of the city centre blocked off by riot police.
A police source said the explosion tore apart a bakery on the rue Trevise in the Grands Boulevards district. The force of the blast shattered nearby storefronts and rocked buildings hundreds of metres away, witnesses said.
An eyewitness who was staying at a hotel nearby said he saw a huge fire erupt in the building blown out by the blast.
"There was broken glass everywhere, storefronts were blown out and windows were shattered up to the third and fourth floors," said 38-year-old David Bangura.
He said that as he approached the scene, a woman was crying for help from the first floor of a building: "Help us, help us, we have a child".
Two helicopters landed on the nearby Place de l'Opera to evacuate victims.