Lyon - French police were hunting a suspected suitcase bomber on Friday after an explosion in the central city of Lyon that injured 13 people, officials said.

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, police sources and local mayor Denis Broliquier said.

Most of those hurt were hospitalised for treatment to leg injuries that were described as light.

President Emmanuel Macron characterised the incident as an "attack" when the news broke during a live YouTube interview ahead of Sunday's European elections. "My thoughts are with the injured," he said.

Paris anti-terrorism prosecutors opened an investigation as police said they were treating the blast as an attempted homicide, and Interior Minister Christophe Castaner headed to the scene.