By Emergency exits at the Moscow concert hall where gunmen killed 137 people could not be opened, some of the survivors have claimed.
Russian media have reported that more people may have died from smoke inhalation than gunshot wounds during the attack on Friday.
Some 28 bodies are thought to have been found in a lavatory and another 14 in the stairwell of an emergency exit.
Trapped people hiding from the gunmen reportedly called emergency services pleading to be rescued as thick smoke filled the building.
Suspected Moscow massacre Terrorist
The suspected Moscow massacre terrorist were frogmarched blindfolded into a building for interrogation over the concert hall shooting.
The suspected killers were held tightly by security guards as they are taken out of vans and brought to the Russian Investigative Committee for questioning.
The four suspected terrorists were seen arriving in an unmarked white van before they entered the concert hall at around 8pm.
Videos previously emerged on social media of the suspects being arrested – with one shaking on his knees and apparently confessing to carrying out the attack.
