French police were searching Thursday for two "radicalized" women linked to a car containing six gas cylinders found in central Paris, with four people already held as part of the investigation. Two new suspects, aged around 20, were arrested late Wednesday in connection with the grey Peugeot 607 found abandoned at the weekend near Notre Dame cathedral, a major tourist draw. Anti-terror investigators are probing the incident, which comes with France on high alert following a string of terror attacks, including last November's coordinated bloodshed in which Islamic State extremists killed 130 people. Speaking on Thursday, President Francois Hollande referred to attack plots that been foiled "in recent days," without elaborating. A first couple, held since Tuesday, are known to the security services for links to radicals. The two women being sought are the daughters of the car's owner — who was also known to authorities for spreading Islamist ideas. He was arrested on Tuesday but released later that day. The daughters have both been described as "radicalized." A bar employee working near Notre Dame raised the alert on Sunday after noticing a gas cylinder on the back seat of the car, police said. The car had no number plates and its hazard lights were flashing Although the cylinder on the back seat was empty, five full cylinders were discovered in the boot of the car. Three bottles of diesel fuel were also found in the vehicle, but police found no detonators. "If it was an attack plot, the method was very strange," a police source said on Thursday. Photographs of the car after it was discovered showed its boot open and the gas canisters placed on the ground in a quiet side street opposite the cathedral. Notre Dame is one of Paris's most popular landmarks, attracting 13 million visitors each year. Speaking on Wednesday, Interior Minister Bernard Cazeneuve said the intentions of those arrested were as yet unknown. Hollande's speech followed a deadly summer in France in which 86 people were killed when a truck ploughed into a Bastille Day crowd in the southern resort of Nice. IS said the truck was driven by one of its followers. Less than two weeks later, two young jihadists murdered a priest near the northern city of Rouen. In May, the head of France's DGSI domestic intelligence service, Patrick Calvar, warned of a "new form of attack" in which explosive devices would be left near sites that attract large crowds. French security services are particularly worried about the danger posed by extremists returning from Syria after fighting with IS forces. Around 700 French nationals are still in Syria, France's top prosecutor said last week.
