A happy, spirited four-year-old beams proudly as she pushes her own pram in a video recorded by her mother to chronicle their day out together in central Ukraine.

An hour or so later she was dead, her short life brought to a brutal end by a Russian missile, the pink buggy overturned in the street and mottled with the little girl's blood, next to her lifeless body.

Liza Dmitrieva, who had Down's syndrome, was being taken by her mother Iryna on Thursday to a therapy centre in Vinnytsia, a city of around 370,000 people, 250 kilometres (155 miles) southwest of the capital Kyiv.

In the footage, which Iryna posted on social media at 9:38 am, Liza can be seen bouncing along the pavement in white leggings and a sky-blue top with what appears to be a daisy stitched onto the shoulder.

Beyond the tribulations of living in a country at war, neither had any special cause to be afraid. They were hundreds of kilometres from the nearest frontline.

"Where are we going, sweetheart?" the woman asks her daughter on camera.

"Alla!" the four-year-old replies, shaking loose strands of wispy blonde hair that had been tied back with a white clip in the shape of a butterfly.

Alla is a common female first name in Ukraine.

"To see Alla?" the mother queries.

"Alla!" the youngster chirps again, an impish grin playing across her face.

Around 80 minutes later a barrage of rockets launched from a Russian submarine in the Black Sea hit Vinnytsia, devastating the city centre and killing 23 people, including two other children.

Liza's mother Iryna lost a leg in the attack and was initially reported to have later died in hospital, but the head of state police said on Friday she was still fighting for her life.

Iryna regularly posted pictures and news of her daughter's exploits and many challenges online, where the little girl had become something of a social media starlet.

Four-year-old Liza Dmitrieva had Down's syndrome, and her mother was taking her to a therapy centre in Vinnytsia Iryna on Thursday to a therapy centre in Vinnytsia
Four-year-old Liza Dmitrieva had Down's syndrome, and her mother was taking her to a therapy centre in Vinnytsia Iryna on Thursday to a therapy centre in Vinnytsia AFP / Sergii VOLSKYI

An Instagram account set up by Iryna and dedicated to Liza amassed nearly 20,000 followers, although that had grown to 80,000 by Friday morning as the horror of the attack sent shockwaves around the world.

"Look how she spins. She loves dresses!" Iryna says in one post, alongside a video of the little girl in a field of lavender, playfully twirling round in her lilac dress.

"I am so glad to be the main example for my child. She copies absolutely everything -- dances, movements, posing in front of a mirror, everyday life stuff," Iryna reveals in another post.

"If I do sports, she does too. I paint, she copies."

First Lady Olena Zelenska said in the early hours of Friday she was "horrified" by images of the overturned pushchair released by local authorities -- only to learn that it belonged to Liza, whom she had met.

"Reading the news, I realised that I know this girl. Knew... I will not write down all the words I would like to say to those who killed her," she wrote on Instagram.

Zelenska explained that she had met Liza while recording a video celebrating the Christmas holidays.

"The little girl managed to paint dye not only on herself and her dress but also all the other children, me, the cameramen and the director in just half an hour."

The first lady posted the video with her message, imploring her Instagram followers: "Look at her alive please. I'm crying with her loved ones."

Russia invaded on February 24. The conflict has killed thousands of people, destroyed cities and forced millions to flee their homes.

Officials said Vinnytsia had sustained widespread damage in what Ukrainian President Volodymyr Zelensky later described as "an open act of terrorism".

Images distributed by officials showed the burnt skeletons of several upturned cars next to a gutted building held up by charred metal frames, with brown smoke billowing from the impact site.

Sergiy Borzov, the head of regional government said on Friday that 13 victims, including the two other children, had yet to be identified.