Paris (CNN) At least 13 people were hurt Friday in an explosion in the French city of Lyon, prompting a national investigation into possible terrorism.

The blast occurred in the early evening in the city's central shopping area. Eleven of the 13 injured were taken to hospital, including a 10-year-old child, the Paris Prosecutor's office said Saturday.

French police are still looking for the person suspected of carrying out the attack, according to a tweet from the French National Police verified Twitter account. Police also tweeted a photo of the man they believed to be "the author of the attack" and asked the public to call with any information.

French President Emmanuel Macron characterized the blast as an attack shortly after it happened, telling an interviewer: "I'm late because there was an attack in Lyon."

Emergency workers wheel a woman on a stretcher to a waiting ambulance in Lyon on Friday.

Investigators believe the explosion may have been caused by a parcel bomb packed with nails, a spokeswoman for the city prosecutor told CNN.

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