It is difficult to imagine the scale of atrocities committed by Russia inUkrainewithout the benefit of video evidence.

And we stayed there until 15th of March documenting everything we could.

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What they documented were horrors to deeply shock the conscience.

Irina, a pregnant woman, is carried away from a maternity hospital in Mariupol bombed by Russian forces.

Irina, a pregnant woman, is carried away from a maternity hospital in Mariupol bombed by Russian forces.Courtesy Sundance Film Festival

Russian missiles striking civilian targets, tanks branded with the Russian Z firing on apartment buildings and homes.

Defenseless people sheltering wherever they could.

I woke up from bombing today, a little girl tells Chernov, tears streaming down her cheeks.

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Director Mstyslav ChernovAP Photo/Felipe Dana

I dont want to die.

But so many children, elderly people, civilians of every age do perish in the hideous attack.

Four-year-old Evangelina dies in a hospital from shelling injuries.

Film how these motherf*****s are killing civilians!

an outraged doctor exclaims.

Ilya, a 16-year-old boy, shares the same tragic fate as Evangelina.

His legs are blown off by a bomb and doctors cannot save him.

His distraught father kisses his sons forehead as Ilya lies motionless on a gurney.

The death toll is overwhelming.

The morgue is full, Chernov says in a somber voiceover, so doctors store bodies in utility rooms.

Kiril, only 18-months-old, will not live even to become a little boy.

His grief-stricken mother, Marina, cannot comprehend the wanton destruction of innocent human life.

I keep asking myself why.

And all Ukrainians are asking themselves why.

And there is no answer.

Thats the most terrifying thing when the suffering has no purpose, it has no meaning.

Chernov is a Ukrainian journalist for the Associated Press, as well as a photojournalist and novelist.

During the siege, weve been able to send only a tiny fraction of what I filmed.

Yes, those were the most important shots.

So there is no way for them to know more or to go deeper.

He filmed the bombing of a hospital maternity ward, one of the most shocking sequences in the documentary.

Irina, a woman on the verge of giving birth, was grievously wounded.

Chernov captured the moment rescuers carried her outside the hospital on a stretcher.

He later learned that Irina and her unborn child did not survive.

In another scene, an injured woman gives birth in the crumbling hospital.

Finally, the infant yells.

His eyes, curiously, open right away.

What a scene of madness to witness as your first view of the world.

In just a matter of days, Mariupol lies in ruins.

The city is slowly dying, Chernov says in voiceover, like a human being.

The Kremlin did not appreciate Chernov and his colleagues documenting the invasion for the world community to see.

The Russians were hunting us down, Chernov wrote in a dispatch for the AP.

They had a list of names, including ours, and they were closing in.

As a result of the growing danger, authorities urged the filmmakers to leave Mariupol.

The siege of Mariupol itself lasted 86 days, Chernov says.

These [first] 20 days are very symbolic.

And its symbolic for Ukraine because its a symbol of resistance.

Mariupol remains under the control of Russian forces.

But across broad sectors of the country the Ukrainian army continues the fight to regain territory.

This is not a film about the past, its a film about the present, Chernov insists.

What we see in the film is not something that happened and [its] over.

What we see in the film is happening right now.

Today, as we speak, other cities are getting destroyed.

And this audience will have more context on what is going on, the director says.

I do hope it will reach international audiences.

That is one of [our] missions.

He adds, Even if it doesnt lets say it doesnt reach all those audiences.