4 suspects arrested after Lyon bomb attack that wounded 13 French authorities say they have arrested four suspects following a blast in the city of Lyon that wounded 13 people last week

PARIS -- French police have arrested four suspects following a blast in the city of Lyon that wounded 13 people last week, authorities said Monday.

TV footage showed a police operation underway Monday in a small town outside Lyon involving officers wearing ski masks. Police had launched a large manhunt after a device exploded Friday on a busy pedestrian street in France's third-largest city.

The prosecutors' office later said three other suspects, including a woman, were detained and formally arrested. According to French media, they included the mother and the brother of the main suspect.

Lyon mayor Gerard Collomb, a former interior minister, said one of the suspects is an IT student who was arrested as he stepped off a bus.

"It's a relief for all Lyon inhabitants. I believe the case has been resolved," Collomb told BFM TV. "If there was a network, it has been identified and will certainly be dismantled."

French President Emmanuel Macron has called the explosion an "attack" but no group has claimed responsibility for the explosion yet. An investigation has been opened for "attempted murder in relation with a terrorist undertaking" and "criminal terrorist association."

Last week, France's counter-terrorism prosecutor, Remy Heitz, described video surveillance that showed a suspect heading toward the center of Lyon on a bike Friday afternoon. The man was seen arriving on foot, pushing his bike along a pedestrian-only street, then leaving a paper bag on a concrete block in the middle of the street near a bakery.

The suspect immediately returned to his bike and left the same way. One minute later, the explosion shattered the glass of a refrigerator in the bakery, Heitz said. Regional authorities said the 13 wounded suffered mostly minor injuries.

It was unclear whether the suspect first arrested Monday was the same person, although Collomb said the detained student was identified thanks to video surveillance.

Investigators at the scene have found screws, ball bearings, batteries, a triggering device that can be used remotely and plastic pieces that may come from the explosive device.

France has been hit by a spate of attacks in recent years, some of them deadly, carried out by people ranging from extremist attackers to mentally unstable individuals.