Eyewitnesses have described the harrowing moment that heavily-armed gunmen mowed down up to 170 people in a Moscow concert hall – with up to 40 estimated to be dead, a source confirm to the Mirror.

It’s believed at least five gunmen stormed the Crocus City Hall in the Krasnogorsky District of the Russian capital on Friday evening at around 9.45pm local time. The group opened fire with machine guns and threw explosives on a densely-populated crowd of people.

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Dead bodies were reportedly seen strewn across the floor of the ‘Picnic’ concert, according to witnesses at the scene. Plumes of smoke and flames were seen billowing from the building in videos captured of the incident. Some of those at the scene were believed to have sought refuge in a basement, while it’s feared others were cut off on the fourth floor – trapped by the fire below.

READ MORE: Moscow shooting UPDATES: 40 dead as 5 gunmen open fire in concert hall in worst attack for decades

Dozens of terrified people desperately tried to flee the volley of gunfire (
Image:
social media/e2w)
While some escaped, there are reportedly 170 casualties at the scene including 40 dead (
Image:
social media/e2w)

Witnesses have spoken out of the horrors which unfolded in the Russian capital. One said: “After we left Crocus, it caught fire from above, and someone remained blocked from inside. It seems to me that bad news will come out now.

“When we left there, the fire was burning with all its might. We ourselves were on the balcony, and were able to get out of there in time. If someone stays on top, there’s no way out.”

The Russian special forces, Spetsnaz, were reportedly storming the hall. Firefighters were said to have begun extinguishing the flames, while they continued to search the area for survivors. The gunmen's intentions are currently unknown and it's not clear whether they are still on the premises.

The gunmen are seen entering the venue (
Image:
BAZA)
The gunmen storm the venue (
Image:
MASH)

The group, who allegedly were dressed in camouflage, started opening fire on the packed venue with their machine guns. “The concert was about to start,” the witness added. “The hall was almost ready, it was 70% full. When we heard the claps, at first we thought it was fireworks.”

Another witness described the hell of when the armed group went upstairs after slaughtering those on the ground floor – which tried with their might to break down some of the “blocked” doors. They said: “Armed people came in from the first floor, we were sitting upstairs.

“When they started shooting at the first floor, everyone started running in panic and a stampede began.”

Flames continued to lick and smoke plumed from the building as firefighters attempted to put out fires (
Image:
AFP via Getty Images)

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A third witness said they saw the torrid events unfold from the balcony as they saw people desperately try and break through the locked doors of the hall as they were bombarded with Molotov cocktails - a type of homemade bomb - and a volley of machine gun fire.

They said: “I was sitting in the hall above, where there were balconies, and we heard gunshots. At first we didn’t understand what happened. “Then I saw how the terrorists came in and started shooting everyone, threw Molotovs [home made bombs], and everything was set on fire.

Emergency services - including the Spetznaz Russian scpecial forces - were reportedly are the scene (
Image:
Will Stewart Images)

“We ran to the exit, but the exit was locked. We ran all over Crocus City, trying to find a way out, but to no avail. We ran into the basement and waited there for the [rescuers], they got us out.”

More than 50 ambulance teams were said to be sent to Krasnogors to provide medical care for casualties, the Moscow Region Ministry of Health told RIA Novosti.

The Mirror has chosen not to show some of the most harrowing footage filmed by witnesses. In one video, at least one of the gunmen is seen unloading an entire magazine of rounds into the cowering crowd in one burst of fire.