French police were on Saturday hunting a suspect believed to have deposited a paper bag containing an explosive device that went off, wounding 13 people in a busy pedestrian street in the city of Lyon the previous day.
France's counter-terrorism prosecutor, Remy Heitz, said an investigation has been opened for "attempted murderer in relation with a terrorist undertaking" and "criminal terrorist association."
He said no group has claimed responsibility for the explosion yet.
Regional authorities said 13 people suffered mostly minor injuries, including 11 who were still in the hospital on Saturday morning.
French President Emmanuel Macron called the explosion an "attack" during a live interview Friday about the European Parliament elections that run through Sunday.
Heitz described video surveillance that show the suspect heading toward Lyon city center on a bike Friday afternoon.
The man was seen arriving on foot, pushing his bike, in the pedestrian Victor Hugo street. He was seen leaving a paper bag on a concrete block in the middle of the street near a bakery, Heitz said.
The suspect immediately returned to his bike and left by the same path. One minute later, the explosion shattered the glass of a cooler in the bakery, Heitz said.
Investigators on the scene have found screws, metallic balls, a triggering device that can be used remotely and plastic pieces that may come from the explosive device.
Police issued an appeal for witnesses Saturday with a photo of the suspect, described as "dangerous", caught on video surveillance.
Heitz said police will release more photos soon. The man was wearing a cap and sunglasses partially hiding his face.