They are of course profoundly sad, but there is also something really quite beautiful about the vigils that follow these terrible events.
The backdrop of the Notre Dame Basilica at night, candles illuminating the pavement outside, was breathtaking.
In the hours before the COVID-19 lockdown forced them off the streets, I joined some of the hundreds of people who travelled here to pay their respects following the knife attack in Nice.
Some cried, others prayed, all paused to remember the three victims.
One of the city’s best-known landmarks, the basilica has sat here on the Avenue Jean Medecin since 1864.
The site of Thursday’s atrocity is just a kilometre away from the spot where a terrorist killed dozens of people on the seafront in a truck attack four years ago.
That tragedy, large scale and brutal, had a profound impact on this southern city.
The horrific detail around the beheading of a 60-year-old woman on Thursday has shocked people here to the core.
Caroline Adam was at the vigil. Twelve hours earlier she’d been in the same spot, witnessing the panic outside and hearing the horror unfolding inside the basilica.
“I was here this morning,” she said, her face partially covered by a mask.
“I heard screams. I’m very shocked by it all. As a Nicoise, I’m very shocked. I heard screams and the police told us to run away quickly.
“I said this isn’t normal. I thought it was a bomb. I keep thinking of those three people, it’s horrible, horrible.”
A local parishioner, Herve Le Bihan also felt the need to pay his respects at the basilica.
He said: “My compassion goes out to all the victims and the families of the victims.
“This not the first time that a church has been targeted, that Catholics have been targeted in their place of worship. It’s very symbolic what they’ve done.
“We need a strong response, I’m very unhappy faced with a situation like this.”
Herve, like many in Nice and elsewhere across France, is desperately worried about the potential for further attacks.
His concerns are understandable. On the same day the 21-year-old Tunisian migrant struck in Nice, police in the city of Avignon shot dead an armed suspect.
And a security guard was attacked and wounded outside the French consulate in the Saudi Arabian city of Jeddah.
It follows a call earlier in the week, by the Islamic State terror group, for a wave of attacks against French interests.
It comes against a backdrop of growing anger in parts the Muslim world over the French government’s decision to back the right of the satirical magazine Charlie Hebdo to republish cartoons of the Prophet Muhammad.
It is, the French president insists, at the very heart of this nation’s secular tradition.
There’s no doubt tensions are running high here. You can feel it.
As I watched the vigil, police rushed to stop a group of around 200 far-right protesters further up the street.
They were eventually allowed to march to the basilica, singing the French national anthem and waving the tricolour as they approached the scene of the attack.
Amid the calls for calm heads, not everyone here is content to mark this latest attack with quiet reflection. There are others much more angry and defiant.