French police have arrested four people over a package bomb explosion in the heart of the south-eastern city of Lyon last week that injured 13 people. A police raid was also under way in a building in the Oullins suburb just south of the city, authorities said. The suspected bomber, a 24-year-old Algerian IT student, was among those arrested. The man’s parents were also arrested and taken in for questioning, as was a second Algerian student who is a family relation, according to the Paris prosecutor’s office, which has jurisdiction over terrorism cases in France. The suspect was previously unknown to police, Lyon’s mayor, Gérard Collomb, said. The suspect was arrested as he got off a bus, calmly putting his hands in the air when he spotted officers approaching, he said. The man’s sister has also been questioned but has not been arrested, prosecutors said. Police had been searching for a man seen cycling near the scene of the blast wearing a green top and Bermuda shorts and carrying a dark-coloured rucksack. He was the target of an extensive manhunt after an explosive device filled with screws and ball bearings was placed in front of a bakery on Friday near the corner of two crowded pedestrian streets. Police circulated photos of the suspect on Twitter, which they said had led to several dozen calls from people with information. Sources close to the investigation said the explosive was most likely acetone peroxide, a volatile compound used in the deadly Paris terror attacks of 13 November 2015. Investigators recovered small screws, ball bearings, batteries, a printed circuit board and a remote-controlled triggering device. Officials later said the charge was relatively weak. Eight women, four men and a 10-year-old girl were injured in the explosion. Eleven of the wounded needed hospital treatment, but none of their injuries are believed to be life-threatening. Some needed surgery to remove shrapnel, authorities said. France has been on high alert following a wave of deadly jihadist terror attacks since 2015 which have killed more than 250 people. Islamic State has been behind many of the attacks, but no one has claimed responsibility for the Lyon blast.