‘’There were the obvious outward signs of police with military weapons, I am sure they were on an alert,’’ Chris Cox told the Mercury after hearing of the deadly, stomach-churning terror attacks in the city he adores.

‘’In fact, I had written that there were inadequate travel warnings for Paris for Australian citizens,’’ the Austinmer-based educator said.

‘’My son and I had travelled there for a funeral, we have been back for about a week. I have been on a few occasions, hence I noted the change in social attitudes.’’

France has vowed a "merciless" response to an unprecedented terrorist atrocity: six co-ordinated attacks that stained Parisian streets with blood and left more than 120 people dead.

Dozens more victims were reported to be in critical condition in hospital.

Mr Cox has friends whose relatives hold senior positions in the police service and ‘’are frustrated with recent events’’.

‘’They really are in a position where they are almost powerless,’’ he said.

‘’There are no-go zones, especially in northern Paris. The tension is obvious, people keep to themselves. I like to think that I understand culture very well.

‘’The problem is that French culture believe in democracy and socialism, quite strongly,’’ he explained.

‘’People should be free to say and do as they please.

‘’However if you come from a different culture you may not completely understand French culture. It is not working.’’

Among his friends and associates in Paris, ‘’this very topic is not far away, they have learnt to live with the problem’’.

‘’The contrast with the French countryside is stark. Very traditional. I never felt safe in Paris and I have travelled extensively. Tehran is a safer city.’’

Paris: On Saturday a thick silence throttled Paris like a hangover. Under grey skies there was muted grief, horror, and above all, pure shock.

Paris' response to the Charlie Hebdo attacks 10 months ago was noisy defiance.

But on Saturday there were no loud demonstrations, no groups linking arms to sing and chant about freedom and solidarity.

The government had forbidden such gatherings as a security measure, in the wake of the terrorist attacks across the city. But anyway there was not the spirit.

Arriving trains disgorged few tourists, only journalists.

Central avenues were sparsely populated, the normal bustle of shoppers culled by fear (and the closure of the Metro).

"I've never seen the city looking like this," one Parisian told France 24. "It's scary. No-one is looking at each other."

The Eiffel Tower was shut, as was the Louvre, as were sports stadiums, schools, public gymnasiums and libraries. They will be shut again on Sunday.

The usual tourist trail was replaced by a new march of grief.

Alone and in small groups, Parisians and visitors were drawn to the sites of Friday night's attacks, bringing flowers, tributes or just their sorrow.

The cafes and bars were taped off and shuttered. Procedural police notices were stuck to the wall, "Prefecture de Police. Infraction: Assassinats en relation avec une entreprise terroriste".

"Offence: murder in a terrorist operation."

Bullet holes dotted windows. Below them small drifts of red sand were still damp with the blood of victims, trod often unnoticed beneath the feet of smartphone-wielding onlookers.

Inside the cafes meals lay abandoned on tables. On bartops, pairs of barely-touched beers bore witness to conversations interrupted, perhaps never to be rejoined.

On the pavements at these crime scenes across the city, tributes began to multiply. Roses rested on bloodstains. Candles flickered beside notes of love and loss.

Some bowed their heads in prayer, others knelt and lit candles. The November wind blew them out, and Parisians kept relighting them.

At the Belle Equipe café, a woman passing on a bicycle broke down into helpless sobs, waving away the media, embracing her confused toddler daughter.

Psychiatrist Dr Vincent Jardon, who treated some of those psychologically damaged by their close encounter with the terrorists on Friday night, said he thought he knew why the mood was different to January.

"It's the number," he said. The number of the dead and injured, the number of the attacks and the attackers.

"It's like a nightmare. They are saddened and they are shocked."

In a condolence book at the local council office, page after page spoke of people's grief and sorrow, their thoughts with the lost and their families and loved ones.

The word "horreur" recurred, page after page.

But there were sparks of defiance. "I hope my country can again become a place of freedom", one had written.

"Je suis Paris," wrote another, in large, bold letters.

The city is not despairing.

"Courage," said one taxi driver, by way of farewell.

At a blood bank opposite the site of one of the shootings, Parisians had queued patiently to donate all day. Eventually, they were asked to go away. They signed pledges to come back the day after, and again after that.

"We have too many people," said Carole Bagot of the Etablissement Français du San (French blood service). "We need people the next day, the next week.

"Hundreds have come, here and to places like this in Paris. They filled with people. They want to give.

"Inside the atmosphere is strange. It is not so comfortable. They are sad, shocked."

Down at Place de la Republique, where the Charlie Hebdo demonstrations had been so raucous, small groups came to leave flowers at the feet of the Liberty statue, while an official loudhailer encouraged them not to linger.

"Still not afraid," said a small sign, in defiance of everything.

A few hundred metres away, under bullet holes in the window of a brasserie bar, candles flickered as twilight fell on the city of light.

Nick Miller, smh.com.au