By Radina Gigova, Mary Ilyushina, and Eliza Mackintosh, CNN

(CNN) -- Hundreds of people protested in the the Siberian city of Kemerovo on Tuesday, calling for a full investigation into a shopping mall fire that claimed the lives of 64 people -- 41 of them children.

Russian President Vladimir Putin, who flew to the city to offer his condolences to the victims' families, blamed the blaze on "criminal negligence" and promised that those responsible would be held accountable.

The fire tore through the Winter Cherry shopping mall on Sunday, the first weekend of spring school holidays, trapping many families who had gathered at a children's play area and movie theater there. Russian investigators said the mall's fire exits were blocked and an alarm system turned off, and witnesses described panicked scenes as shoppers attempted to flee the building.

A video released by Putin's press office showed Putin laying roses at a makeshift memorial scattered with candles and toys, flanked by his security detail.

"What is happening here -- this was not a combat situation, not an unexpected methane outburst in a mine," he said.

"People came to rest, children. We talk about demographics and lose so many people because of what? Because of criminal negligence and carelessness."

The origin of the fire has yet to be determined.

The Kemerovo blaze comes at a delicate domestic political moment for Putin, who sailed to a re-election victory on March 18. As the scandal about the fire tragedy unfolded, western allies led by the EU and the US announced a coordinated expulsion of more than 100 diplomats in response to the poisoning of Russian former spy Sergei Skripal and his daughter Yulia in Britain.

Putin did not meet with demonstrators in Kemerovo, who had gathered in front of the local administration office to call for a full probe into the fire. Members of the distraught crowd cast doubt on the official death toll and demanded that the Forensic Examiner's Office verify the number, Russia's state news agency Tass reported.

Footage from the scene showed riot police standing between protesters and the municipal building.

"A lot of children died. They died because of irresponsibility of management," one local resident, Svetlana Shestakova, said. "I am shocked that they are hiding the truth from us."

In response to the allegations, Kemerovo Mayor Ilya Seredyuk and members of a civic action group have gone to the mortuary, according to Tass.

Horrific scenes

The Kemerovo fire is one of the deadliest blazes in Russia in recent years, according to state media.

"It's just a horror ... it's hard to describe what happened today ... it was a normal day off," said eyewitness Anna Zarechneva on Instagram.

She was in the mall's cinema when the fire broke out, and said moviegoers had little warning until the blaze was well underway.

"No fire alarm to be heard. The crowd broke through one narrow door. The second exit for some reason was closed," Zarechneva wrote.

"Having jumped out of the cinema, we saw dense black pungent smoke, which completely filled the children's playground and the 2nd cinema hall -- they were completely invisible. There was already no air."

Preliminary investigations point to the fire having broken out outside the cinema. Four people have been detained in connection with the fire, authorities said.

"Serious violations were allowed, both when the shopping center opened and after, during its operation. Fire exits in the shopping center were blocked," said Svetlana Petrenko, spokeswoman for the Russian Investigative Committee.

Early images from the scene showed thick black smoke pouring from the shopping center, a former sweet factory, as firefighters continued to battle the flames after dark.

As around 100 people were evacuated, others were trapped by the fire inside. Witnesses told Russian media they saw people jumping from the windows in desperate efforts to escape.

The shopping mall, which has an overall area of 23,000 square meters, opened in 2013. It has a parking lot for 250 cars, shops, a bowling, a children's center, a movie theater, and a petting zoo, according to state media.

The-CNN-Wire

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