MOSCOW — At the end of a month that has seen him unveil new “invincible” missiles, announce a space mission to Mars and secure a sky-high vote in Russia’s election, President Vladimir V. Putin faced a grim reality on the ground Tuesday: a nation enraged by the deaths of children trapped in a burning mall in Siberia.

Mr. Putin traveled to the town of Kemerovo to lay flowers next to a memorial for the at least 64 people, many of them children, who died in the fire on Sunday. Some of them died as they banged on locked exit doors and screamed into cellphones for help from their parents.

“How could this ever happen?” Mr. Putin asked local officials, echoing a question now being asked across Russia by a population that just recently voted overwhelmingly to re-elect a president who, during his previous 18 years in power, repeatedly boasted of making Russia strong and safe.

Public anger at the fire — and claims that official bungling and corruption played a part — drowned out the Kremlin’s fury over Monday’s expulsion of Russian diplomats by 23 countries. Even on state-controlled television, news about the fire pushed aside routine denunciations of the West just as four more countries ordered out diplomats over a nerve-agent attack for which London has blamed Moscow.