PARIS (AP) A young woman wept while complete strangers on Paris' normally bustling subway stared at each other in solidarity at noon Thursday, as metro trains ground to a halt for one minute of haunting silence.

Muslims at the Paris Mosque fell quiet too, a day after the biggest terror attack on French soil in living memory. Catholics listened inside Notre Dame Cathedral as its gargantuan bell tolled, the sound echoing around the Ile de le Cite.

President Francois Hollande ordered flags flown at half-staff, and the Eiffel Tower will switch off its lights and shroud tourists in dark.

Thursday marked a moment for an often-divided France to come together as one nation to mourn. Twelve people were killed in the shooting on and around the premises of satirical newspaper Charlie Hebdo in central Paris on Wednesday, in which the gunmen shouted "Allahu akbar!" as they fired.

Now, the French are trying to understand why.

One Algerian-born grandmother, Algdia Henneche, wept.

"We're all in danger now. In the shops, in the bus. I've brought up seven children here. France is multicultural we welcome all countries. Now for my grandchildren, what will happen?" asked the 69-year old.

Magali de Rapheles, a 22-year-old student, shed a tear as she observed the silence on No. 13 subway line.

"I'm still in shock. A minute of silence is important to remember and to process even on the metro. I've found it hard to do anything since yesterday," she said.

Others were more defiant.

"How is this possible in the nation of human rights?" asked Liliane Graine, a 58-year-old local councilor in the southern suburb of Montrouge.

"What we mustn't do now is put Muslims and jihadis in the same bag. We must be on alert, and make sure this terrorism doesn't lead to increased racism," she added.

The rector of the Paris Mosque, Dalil Boubakeur, has been vigilant and called on Muslims country-wide to observe the moment of silence and honor victims of this "exceptional violence."

Boubakeur also called on all French imams to firmly condemn the tragedy and address it in their Friday prayers.

One sandwich-maker, Ben Ammar, who identified himself as a Muslim, shrugged.

"Of course, I keep working I have a business to run. Why should this concern me? I've seen it on TV. I'm not afraid," he said.

In the National Assembly and the Senate, lawmakers on all sides stopped bickering to observe the silence requested by Hollande.

What followed, at one minute past noon, couldn't have been predicted. Politicians reached out to each other in song, breaking out together into a rousing rendition of the French national anthem, the Marseillaise. Then and now, it's seen as a call against intolerance, for the country, in all its colors, to unite.