Three people died and seven are critically ill after an Instagram star’s pool party stunt turned to tragedy.

The Sun reports that victims reportedly suffered carbon dioxide poisoning when a huge load of dry ice was chucked into the water to create a spectacular “steam show” effect.

Moscow mum blogger Ekaterina Didenko, who has 1.1 million followers, was celebrating her 29th birthday in a pool and sauna complex in the Russian capital.

Her husband Valentin, 32, was among three fatalities after he unloaded 25kg of dry ice, or frozen carbon dioxide, into the pool.

It was meant to delight partygoers by producing huge clouds of theatrical smoke.

But guests immediately began suffering severe breathing problems and fainting, and some reportedly had chemical burns.

Natalia Monakova and Yuri Alferov, both 25, were confirmed dead at the scene, according to reports in Russia.

IT specialist Valentin Didenko, also known as Valya, died in hospital.

media_camera Natalia Monakova died at Ekaterina Didenko's 29th birthday party when dry ice was thrown in a pool. Picture: Instagram

Ms Didenko was initially reported to be among the dead but posted a video online from her bed in hospital before she knew her husband had died.

She told followers: “I am alive, I am behind the doors of an intensive care ward.

“I don’t know who died. Valya is in the intensive care. I don’t know what state he is in.”

media_camera Ekaterina Didenko was celebrating her 29th birthday. Picture: Instagram

Later she posted another video of herself weeping as she told followers her daughter Nastya was asking: “Where is Daddy?”

She said after being released from hospital: “Valya is not with us any more.

“Or Natasha (Natalia). Or Yura (Yuri). I can’t tell you anything else.

“I did not cry yesterday. Today I just exploded.

“I thought it was not true, it was a nightmare.

“Nastya woke up today – ‘Where is daddy?’ I do not know what to say to her …

“She is asking me: ‘Why are you crying?’”

media_camera An image of dry ice. Picture: Supplied

Dry ice is frozen carbon dioxide and produces heavier-than-air vapour when mixed with water.

In high concentrations it can cause levels of carbon dioxide in blood to soar, blocking oxygen from reaching vital organs.

The three who died were in the water at the time, reports say.

Reports said Natalia and Yuri died from pulmonary oedemas after breathing the gas.

One expert questioned if this was normal dry ice or contained “another substance” that worsened the poisoning.

Valentin Didenko had wanted “to create an impressive steam show” as party guests jumped into the pool.

Moments earlier guests had been laughing and clinking glasses, social media pictures show.

media_camera Ekaterina Didenko's husband Valentin Didenko was killed when dry ice was thrown into a pool. Picture: Instagram

Mother-of-two Ekaterina, a qualified pharmacist, is a popular Instagram blogger who gives advice on medicines for home use.

She also shares intimate moments of her own life and in some videos she is seen filming chemical experiments with her young daughter.

The Russian Investigative Committee confirmed a criminal case was opened into causing death by negligence.

In 2018, an ice cream salesman’s wife and mother were found unconscious in a car in Washington State, US – apparently from the vapour from four dry ice coolers.

This article originally appeared in The Sun and is republished here with permission