The Police in France are still questioning a man suspected of carrying out an attack on a factory near Lyon, in which a man was beheaded.
Prosecutors said 35-year-old Yassin Salhi, caused an explosion by ramming his car into an area containing flammable liquids.
His boss, the owner of a delivery firm, was found beheaded alongside flags with Arabic inscriptions.
Reuters reports that Salhi is being held in Lyon, where he was refusing to respond to interrogators on Saturday, according to a source.
His wife, sister and a fourth person are also in detention.
Salhi is known to have associated with Islamists for years and had previously been flagged by French authorities as a potential risk, but there has been no claim of responsibility for the attack.
While an anti-terrorist inquiry has been launched, Paris Public Prosecutor, Francois Molins, said it would be premature to make any conclusions at this stage.
”Questions remain over the exact chronology of events, what happened when he arrived, the circumstances of the decapitation, the motivation and whether there were accomplices,” he said.
French authorities are investigating a crash in Argentina, involving two helicopters, in which eight French nationals lost their lives.
Three popular French sports personalities including two Argentine pilots are among the dead. An amateur video shows the two helicopters collide during the filming of a TV survival show, known as Dropped, which airs in France.
French President, Francois Hollande, has reacted to the helicopter crash disaster, calling it “a cause for immense sadness”.
One of the French sports personalities who died in the crash was Florence Arthaud, 57, a skilled sailor who won the 1990 Route du Rhum, the prominent solo Atlantic race.
Another personality was Olympic swimmer, Camille Muffat, 25, who won 3 medals in the 2012 London Olympics and Olympic boxer, Alexis Vastine, 28, a bronze medal winner at the 2008 Beijing Olympics, in the light-welterweight category.
The Argentine pilots who also lost their lives in the helicopter crash were Juan Carlos Castillo and Roberto Abate.
Other 5 French nationals that died were said to have worked for Adventure Line Productions (ALP), the company making the programme. They are Laurent Sbasnik, Lucie Mei-Dalby, Volodia Guinard, Brice Guilbert and Edouard Gilles.