(CNN) -- The number of people who died when fire ripped through a shopping center in the Siberian city of Kemerovo has risen to 64, many of them children, authorities said.
Around ten people are still missing after the blaze broke out on Sunday afternoon, when the mall was packed with shoppers and cinema goers. Ten others are in hospital, Vladimir Puchkov, the head of the Ministry of Emergency Situations told journalists Monday.
Preliminary investigations point to the fire having broken out in the cinema hall area of the four-story Winter Cherry shopping mall in the center of Kemerovo.
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 cinema, and a petting zoo, according to the state news agency, Tass.
Rescue workers say they have checked the first and second floors and are checking the third but have had difficultly making it to the fourth floor where the fire is believed to have started.
"They can not make it through yet, as the temperature is high there," the first deputy head of the regional department of the Ministry of Emergencies, Evgeny Dedyukhin, told Tass.
Earlier Svetlana Petrenko, a Russian Investigative Commitee spokeswoman, told Tass that four people had been detained and questioned in relation to the fire. Among those detained include "the tenant of the premises where the epicenter of the fire allegedly was," Petrenko said.
Sputnik, a state-funded news outlet, reported the head of the city's fire department Sergei Yakovlev as saying the blaze had spread via flammable thermal insulation, making it difficult to put out.
It is not yet known how the inferno began.
People were gathering at the scene Monday morning to lay flowers and toys, Sputnik reported.
Russian officials say 20 psychologists are working with relatives of missing people.