At least 13 people were injured in an explosion in the French city of Lyon after a man left a suspected parcel bomb on a shopping street, officials said.

Most of those hurt were hospitalised for treatment to leg injuries that were described as "light". The Paris counter-terrorism prosecutor has opened a probe into the blast.

No one has claimed responsibility for the act as of yet, said Paris prosecutor Rémy Heitz at a news conference on Saturday. He said investigators found screws, metal marbles, seven small batteries, a printed circuit board, and a remote-controlled trigger device.

The suspect was captured on security video leaving a bag in front of a bakery shortly before an explosion occurred at around 5:30 pm local time, police sources and local mayor Denis Broliquier said.

The police released a photo of the suspect as part of a call for witnesses to come forward to help find the man who is still at large. He is wearing a dark-coloured balaclava and sunglasses, pushing a bike.

They said the individual was dangerous and told the public not to approach him under any circumstances but provided a number for anyone with information on his whereabouts to call.

The mayor of Lyon and former French interior minister Gérard Collomb expressed his "deep emotion" and "surprise" that the event had taken place.

"We wouldn't expect an attack like this to happen in Lyon," Collomb told AFP, describing the third largest city in France as "rather a quiet city." Collomb returned to Lyon on Saturday morning and was flying back from Japan when the blast occurred, according to AFP.

Collomb also expressed his sympathy for the victims and in particular a little girl who was hurt.

French interior minister Christophe Castaner and Paris prosecutor Rémy Heitz arrived at the site on Friday night but did not speak to the press.

By 6:00 am on Saturday morning, the security perimeter had been lifted, but glass still littered the street where it exploded.

"My customers that told me that it was a person on a bike that was wearing a balaclava," a local shop worker told Euronews.

Luckily no one was killed," she added.

"I was a block away and I heard it. They locked us in the store. I came out 10 minutes later and the police etc were arriving," Canadian travel writer Kathy Buckworth told Euronews.

The explosion was "like a bomb, extremely loud," she said.

Glass still littered the street Saturday morning. Euronews

The incident occurred around 17h40 CEST on Friday, according to the French interior minister.

The explosion took place in the second arrondissement of Lyon on the angle where Rue Victor Hugo meets Rue Sala in a busy shopping area.

Minister of the Interior Christophe Castaner ‏said he had sent instructions to all prefectures to reinforce security at the public sites hosting sporting or cultural events.

Police sources said that there would be an elevated police presence in Lyon Saturday due to the ongoing search for the suspect and the 28th round of yellow vest protests in the area.

French President Emmanuel Macron described it as an "attack" with no fatalities.